Summary of the
Single Recent Articles
Study of the formation of benzothiadiphosphole system:
a new domino reaction!
Recently, the course of this anomalous reaction has been studied by 1H
and 31P NMR and it was seen that benzothiadiphosphole system 2 (or cis-1)is formed by a domino reaction
as reported below. Probably, because of the relative complexity of the
structure, no chemists, in the past, observed its formation from this simple
and well-known reaction. It should be noted that the final phosphonium salt G
does not give, after treatment with water the expected product of hydrolysis 3
but it gives 2a (or cis1) as a product of reduction. At that
time, this result was unexplained.
A One-Pot Synthesis at Room Temperature of Various
Cyclic Phosphine Derivatives by Simultaneous addition of Bis- and
Mono-Grignard Reagents To Our "Butterfly" Phosphorus Donating
Reagent.
The
synthesis of cyclic phosphines is of considerable current interest principally
because these compounds are the most commonly studied ligands for applications
in homogeneous catalysis. Generally, the reported syntheses of 1-substituted
cyclic phosphines are related to the interaction of bis-Grignard reagent of
dihaloalkanes with dihalophosphines or the use of the cyclization reaction of
dihaloalkanes with metallated phosphines, or the addition of primary phosphine
to olefins . However, the above reported syntheses require multi-step
procedures and/or the use of highly pyrophoric primary phosphines requiring
special attention for their manipulation, or the use of alkyldichlorophosphines
with their extreme hydrolytic and oxidative instabilities, when R= alkyl.
In addition, during the reaction the alogenophosphines produce HCl, which might
be dangerous to the final product.
Now
we have found1 a synthesis, in good yields, of the 1-alkyl and
1-phenyl derivatives of the five-, six-, seven- membered cyclic phosphines 3
or their sulfides (4, 5, 6). It proceeds in a one-pot
reaction with simultaneous addition of three reagents (see scheme 2) and uses
the our phosphorus donating reagent 1. This reagent have a
"butterfly" structure (as depicted in Scheme 1) and this arrangement
is fundamental to explain its unusual reactivity in our procedure.
The
reaction of 1 with two equivalent of bis-Grignard 2 gives, in a
one-step procedure at room temperature and after treating with water, the
corresponding cyclic phosphine 3, bearing in 1-position the same
alkyl chain of the starting dihaloalkane (see Scheme 1). It should be noted
that the conversion to sulfide occurred in situ by treatment, at room
temperature, the final reaction mixture with elemental sulfur. The yield is
good for five- (82 %) and six- (60%) membered cyclic compounds while it is much
lower (20%) for the seven-membered ring. These results indicate clearly that it
is more easy the formation of five-membered rings over six-membered rings. This
result is in contrast with many other well-known reactions involving ring
closure in which, generally, six-membered rings are more favoured over
five-membered rings. Our results can be easily explained with the intervention,
in these reaction, of hypervalent phosphorus intermediates (penta- and
hexacoordinate) with a trigonal bipyramid or an octahedral structure. In these
hypervalent phosphorus species the presence of a small ring (or preferentially
more) is a factor of great stability, reducing the crowding. If an additional
small ring is generated during the reaction we have a further stabilization of
these intermediates. In recent works2, a series of cyclic compounds
containing penta- and hexacoordinate phosphorus has been reported, whose
crystal structures show folded geometries containing a "dibenzo"
moiety very similar to our molecula 1. We think that the rigid
"dibenzo-butterfly" moiety with its bicyclic condensed and delocalized
system enhance the stability of these reported hypervalent phosphorus species
such as our hypothetical intermediates A' and A. In our case, the
"dibenzo-butterfly" moiety is present already in the starting reagent
1.
Moreover,
when we add bis-Grignard 2a (or 2b), the formation of another
five- (or six-) membered cycle around the phosphorus atom is another additional
factor of stability of pentaccordinate intermediates such as A'
and subsequently hexacoordinate A. As a consequence we have that the
cyclization reaction is preferred over the simple substitution reaction.
Then,
this observed favored cyclization prompted us to synthesize, always in a
one-pot one-step procedure, phosphine sulfides 4 by simultaneous
addition of an equimolar mixture of a bis-Grignard 2a (or 2b)and
a mono-Grignard RMgBr (R = n-butyl or n-pentyl, respectively) to an equimolar
amount of 1. In this manner, after treatment with S8 and water
(see scheme 2) we obtained directly 4a (or 4b), in good yields
(60-70%)Scheme 2. In similar manner, when we used bis Grignard 2a with
RMgBr (R = n-pentyl), we obtained 1-pentylphospholanesulfide 5 in 65%
yield, while when we used 2 withPhMgBr we obtained 1-phenyl cyclo
phosphine sulfide 6 (60% yield). Obviously, if the reaction mixture wase
treated only with water, the corresponding cyclic phosphines can be obtained,
as reported in Scheme 2. A general pathway for the reaction is proposed (see
Scheme 3).
In
conclusion, we have described a new facile one-pot preparation of substituted
cyclic phosphines or their corresponding sulfide from simultaneous addition, at
room temperature, of a mixture of mono-Grignard and a bis-Grignard to the new
phosphorus donating reagent 1 in which its butterfly arrangement
explains its reactivity. In addition, the route is flexible and should permit a
variety of substituents in the chain or/and in the cycle including chiral
structures .
1) Baccolini, C. Boga, U. Negri, Synlett 2000,
1685-1687.
One-Pot Synthesis of 1-Alkenyl Derivatives of
Phospholane and Phosphinane: New Classes of Compounds
Subsequently
we have tried to obtain with our procedure, 1-alkenyl derivatives of
phospholanes and phosphinanes using in the second step Grignard reagents
containing alkenyl group hoping that the double bond does not react with any
intermediates or by-products of the reaction.
In
this manner we obtained, as reported in Scheme 3, 1-alkenylphospholane sulfides
6a,b,c and 1-alkenylphosphinane sulfides 6d,e,f
(70-80% yield) by addition, in the first step, of equimolar amounts of a
bis-Grignard 2 (n = 1 or 2) and 1; then, in the second step,
addition of a mono-Grignard RMgBr (R = alkenyl group) and final treatment with
S8, always at room temperature.
If
the reaction mixture was treated with water instead of S8, the
corresponding cyclic phosphanes 5, which are air-sensitive compounds,
were obtained.
As
you can see, this synthesis, at room temperature, of title compounds is
obtained by a one-pot reaction sequence involving transfer of a phosphorus
atom from a benzothiadiphosphole to incoming nucleophilic bis- and mono-Grignard
reagents. In addition we have noted, with surprise, that 1-alkenyl derivatives
of tri-coordinate phospholane and phosphinane are to date unknown. Probably it
is not possible or very difficult to obtain 1-alkenyl cyclophosphane
derivatives with the hitherto known procedures.
Eur.J.Org.Chem.2001
, 3421
New General One-Pot Synthesis of 1-Alkoxy Cyclic
Phosphine Derivatives
Treatment,
at room temperature, of benzothiadiphosphole 1 with bis-Grignard 2
and with sodium alcoholate and finally with S8 afforded 1-alkoxy
cyclic phosphine sulfides in good yields. In similar manner sodium
phenylthiolate gave the corresponding 1-phenylsulfanyl cyclic phosphine
derivatives.
Synthesis 2001 ,1938
Graphical Abstract of above Results
Simple and General Synthesis of New 11H-11λ5-Dibenzo[ c,f] [ 1,2,5] dithiaphosphepine Derivatives
Treatment,
at room temperature, of benzothiadiphosphole 1 with bis-Grignard 2
gives intermediate A which, after 3 hours gives intermediate A'.
Subsequent addition of RMgX or sodium alcoholate and final treatment with S8
and water affords the new heterocyclic system 5 in good yields. From the
reaction mixture it is also possible to obtain the cyclic phosphine sulfide 6
or its dimeric form 7.
Tetrahedron Letters 43, (2002 )9299-9302
New Light on Friedel -Crafts Phosphonation of
Anisoles: Unexpected Insertion of Phosphorus Moiety into O-Me Bond
Since
the last century, the Friedel-Crafts-type reaction using PCl3 and
AlCl3 has been of interest for the direct phosphonation of an
aromatic ring. However, this reaction is very sensitive to the type of
substituents present on the aromatic ring. In particular, very limited success
and conflicting results have been reported when the reaction is carried out
with anisoles. For example, anisole, upon treatment with PCl3 and
AlCl3 gave complex reaction mixtures depending on the quality of
AlCl3 with poor yields of methoxy-substituted arylphosphonous
dichloride or phenylphosphorodichloridite and large amounts of undistillable
residues:
To
increase the yield and the selectivity of this phosphonation reaction the use
of SnCl4 and very recently the use of BiCl3 have been
reported. In the past years we discovered5 an unusual reaction of
PCl3 and AlCl3 with thioanisoles which gave a new
heterocyclic system (fused 1,2,3-benzothiadiphosphole) containing the P-PS2
unit.( as reported above).
Then,
we thought to study again the reaction of anisoles 1 with AlCl3
and PCl3, in order to find results which might explain the reported
formation of large amounts of undistillable residues.
Now
we have found that anisoles 1, reacting with AlCl3 and PCl3
with appropriate reagent ratios, give, in good yields, the corresponding diaryl
methylphosphonates 2 or the methylphoshinates 3b,c and the
methylphosphine oxides 4b,c. This unexpected in situ
methylphosphorylation explains the reported limited and conflicting results to
obtain methoxy-substituted arylphosphonous dichloride with the same reagents.
The
suggested mechanism of P insertion into O-ME bond is reported below:
SYNLETT , 1999,822
One-pot synthesis of unsymmetrical aryl
methylphosphinates by insertion of dichlorophosphines into O-Me bond of
anisoles
This
letter describes a new one pot method for the synthesis of unsymmetrical aryl methylphoshinates
by insertion of phosphorus moiety into O-Me bond of anisoles These products are
very difficult to obtain with other reported methods requiring several steps.
When
we used RPCl2 with R=cyclohexyl the reaction gave formation of the
corresponding aryl cyclohexylmethylphoshinates (8a,b) in good yields.
When we used PhPCl2 with we have good formation of 7a (50%)
but small amounts of 7b (20%). In this case is preferred the formation
of phosphinoxide 9 (40%) due to the competitive attack on the para
position of anisole. The best selective formation of 7 or 8 was
obtained with anisole 3a : AlCl3 : RPCl2 ratio of
1 :1: 1, at room temperature for 30-35h or at 60°C for 4-6 h in atmosphere of
dry nitrogen and without solvent. Compound 10 or 11 were obtained
in small ammounts as by-product .When we use a ratio of anisole 3 : AlCl3
: RPCl2 ratio of 2 :1: 1, we have good formation of
diarylphosphonate 10 or 11 (45-60 %). In all cases, the
structures were assigned by comprehensive spectral data.10
Tetrahedron Letters 2001, 6121
One-Pot and Multi-Step Syntheses of a New Fused-ring
System: [1,2,3]Benzoxadiphospholo [2,3-b] [1,2,3] benzoxadiphosphole
Anisoles
4, reacting with AlCl3 and PCl3 in appropriate
reagent ratios and reaction conditions give in a one-pot procedure, after
quenching with water, the new fused bicyclic system derivatives 5 and 6
as major products. An alternative multi-step synthesis of this system is also
reported. In the last step of this second procedure we use bis-(o-methoxyaryl)phosphine
oxides 11 and again the couple AlCl3 and PCl3.
Diarylphosphine oxides 11 are obtained by a new simple method and it
uses Grignard derivative of o-bromoanisoles, PCl3 and finally
quenching with water.
EUJOC
2001, 2229
Unexpected reactivity between aromatic nitro
compounds and PCl3/AlCl3. A new one-pot synthesis of
phenazines
The
reaction between 4-nitroalkoxybenzenes 7 and PCl3/AlCl3,
when carried out in appropriate molar ratio, gives a prevalent formation of
diazenes 8 and 2,7-dialkoxyphenazines 9 with their new chlorinated
derivatives 10-13. These compounds are obtained, in satisfactory yield,
in a one-pot procedure, in mild conditions, from commercially available and
safe starting materials. In this reaction both the reagents PCl3 and
AlCl3 play a fundamental role in obtaining the products, and this
method might be applicable to other 4-alkoxynitrobenzenes.
Tetrahedron Letters 2003, 44,2649-53
ATOM ECONOMIC ONE-POT
SYNTHESIS OF SECONDARY CYCLIC PHOSPHINES
Angew. Chemie. Int.
Ed. 2004, 43, 3058-3060
Up to date, secondary cyclic phosphines are
reported to be obtained only in very low yields (3-5%).
We report an efficient and very economic new
method for the one-pot preparation of secondary cyclic phosphines (five and six
membered). This method consists of the reaction, at room temperature, between
the reagent 1 and one equivalent of bis-Grignard 2, followed by treatment
with water to give cyclic phosphanes 5 in 70-80% yields and the new
compound 6. Simple treatment with PCl3 of 6 makes it
possible to quantitatively and immediately regenerate the starting reagent 11,
which can be reused without further purification. Then, this synthesis is also
atom economic and environmentally friendly because the by-product 6 is
easy transformed in the starting reagent 1.
1) For a previous work
about the use of 1 see :G. Baccolini, C. Boga, U. Negri, Synlett 2000,
1685-1687.
Simple and general synthesis of new 11H-11λ5-dibenzo[c,f][1,2,5]dithiaphosphepine
derivatives
Graziano Baccolini
,
a,
, Carla Bogaa,
Giulia Guizzardia
and Stefano Ponzanoa
aDipartimento di Chimica Organica ‘A.
Mangini’, Università di Bologna, Viale Risorgimento 4, I-40136 Bologna, Italy
Abstract
Treatment
at room temperature of benzothiadiphosphole 1 with bis-Grignard 2
gives intermediate A, which after 3 h gives intermediate A′.
Subsequent addition of RMgX or sodium alcoholate and final treatment with S8
and water affords the title compounds 5 in good yields. From the
reaction mixture it is also possible to obtain the cyclic phosphine sulfide 6
or its dimeric form 7.
Graphic
Tetrahedron Letters
Volume 43, Issue 51, 16 December
2002, Pages 9299-9302
Solvent-Free Reaction of Some 1,2-Diaza-1,3-butadienes
with Phosphites: Environmentally Friendly Access to New Diazaphospholes and E-Hydrazonophosphonates
and
The
present article describes the reaction between 1,2-diaza-1,3-butadienes and
trialkyl phosphites, under an atmosphere of nitrogen and under solvent-free
conditions, to give alkyl 3,3-dialkoxy-2H-1,2,3
5-diazaphosphole-4-carboxylates that, in turn,
are converted into corresponding E-hydrazonophosphonates by treatment
with THF:water (95:5). These latter compounds are obtained directly by the
reaction of 1,2-diaza-1,3-butadienes with trialkyl phosphites in the presence
of air. These compounds are useful for the further preparation of dialkyl
(5-methyl-3-oxo-2,3-dihydro-1H-4-pyrazolyl)phosphonates and
2-dialkoxyphosphoryl-1,2,3-thiadiazoles.
J. Org.
Chem.,
|
New General One-Pot Synthesis of 1-Alkoxy Cyclic
Phosphine Derivatives |
|
Graziano Baccolini*, Carla Boga, Rezio A. Buscaroli |
|
Dipartimento di Chimica Organica ”A. Mangini", Università di
Bologna, Viale Risorgimento 4, 40136 Bologna, Italy |
|
Received 26 June 2001 |
Abstract
Treatment,
at room temperature, of benzothiadiphosphole 1 with bis-Grignard 2, sodium alcoholate and finally with S8
afforded 1-alkoxy cyclic phosphine sulfides in good yields. In a similar
manner, reactions with sodium phenylthiolate gave the corresponding
1-phenylsulfanyl cyclic phosphine derivatives.
Synthesis 2001: 1938-1940
ù
|
Transformations of
benzothiadiphosphole system: General one-pot synthesis of
1,2,5-dithiaphosphepines and their precursor phosphanethiols |
|
Graziano
Baccolini 1 *, Carla Boga 1, Marzia
Mazzacurati 1, Magda Monari 2 |
|
1Dipartimento di
Chimica Organica, Università di Bologna, Viale Risorgimento 4, I-40136
Bologna, Italy |
|
email: Graziano Baccolini (baccolin@ms.fci.unibo.it) |
G.
Ciamician
,
Via Selmi 2-40126, Bologna, Italy
|
Treatment, at room temperature, of
benzothiadiphosphole 1 with BrMg(CH2)5MgBr gives
intermediate A, which was allowed to stand for about 3 h at room
temperature. The subsequent addition of RMgX to the reaction mixture and the
final treatment with an excess of S8 and water affords the
dithiaphosphepine sulfide 8 in good yields. The structure of this new
heterocyclic system, containing both an S |
One-pot synthesis of unsymmetrical aryl
methylphosphinates by insertion of dichlorophosphines into the O---Me bond of
anisoles
Graziano Baccolini,
a,
and Carla Bogaa
aDipartimento di Chimica Organica, Università, Viale
Risorgimento 4, I-40136 Bologna, Italy
Received 21 June 2001;
accepted
4 July 2001.
Available
online 7 August 2001.
Abstract
This
letter describes a new one-pot method for the synthesis of unsymmetrical aryl
methylphoshinates by insertion of phosphorus moiety into the O---Me bond of
anisoles. These products are very difficult to obtain with other reported
methods requiring several steps.
Graphic
|
Tetrahedron Letters |
High Atom-Economical One-Pot Synthesis of Secondary
Phosphines and Their Borane Complexes Using Recycling Phosphorus Donor Reagent
Dipartimento di Chimica Organica "A.
Mangini" Alma Mater Studiorum-Universita' di Bologna, Viale Risorgimento
4, 40136 Bologna, Italy
baccolin@ms.fci.unibo.it
Received February 2, 2006
|
Abstract: |
|
|
A general new method for the one-pot
preparation of secondary phosphines 11 and in situ generation of their
borane complexes 12 is described. This method consists of the sequential
addition, at room temperature, of equivalent amounts of R1MgBr and R2MgBr
to 1 equiv of the phosphorus atom donor reagent 1. Final treatment with
water gives secondary phosphines R1R2PH (or the
corresponding phosphine-borane complexes if treated with BH3·THF)
and the end product 6, which can be recycled.
Org. Lett.,
Graziano Baccolini,
a,
, Carla
Bogaa
and Marzia Mazzacuratia
aDepartment of Organic Chemistry, ‘A. Mangini’, Alma Mater
Studiorum—Universita' di Bologna, Viale Risorgimento 4, 40136 Bologna—Italy
Introduction
The
nature of the mechanism by which a Grignard reagent reacts with electrophiles
still is an open question. This probably means that different intermediates can
be accounted for this process depending on the reaction conditions and the
electrophilic system used. There are two possible reaction routes: the polar
concerted mechanism, which is hypothesized to proceed via a four-center
transition state; and the stepwise electron-transfer mechanism[1]
(Scheme 1).
The
above two mechanisms may compete and the products from the two processes will
often be the same.
But
the problem with this reaction is that no-one really knows precisely what
happens during the initial step of this addition reaction. stepwise
electron-transfer mechanism[1] (see Scheme 1).
It should be noted that the phosphorus atom can have
very stable hypervalent coordinations[2] making it possible to observe
its hypervalent states during the course of a reaction. In the case of the
carbon atom, by contrast, these hypervalent states are possible but very
difficult to be identified.[3]
Herein we report the first instance of the concrete
evidence for possible intermediates formed during the initial stage of a
Grignard addition reaction between t-BuMgCl
or t-PentMgCl and a P-S bond.
These intermediates have been identified by 31P
NMR spectroscopy and have a four-center
structure, in agreement with that of the classic four-center transition
state that has been hypothesized for this type of reaction, and they are
assumed to present a carbon atom in a hypervalent state. The reaction course
was monitored, by 31P NMR spectroscopy, also using other Grignard
reagents.
Scheme 1. Two
possible mechanisms for the addition reaction of Grignard reagents
Graphical abstract
References
[1] a) T. Holm, I. Crossland Mechanistic Features of the Reactions of
Organomagnesium Compounds in Grignard
reagents New developments (Ed.H. G. Richey, Jr.), Wiley Chichester, 2000, Chapt. 1. b) J. F. Garst, M. P. Soriaga, Coord. Chem. Rev. 2004, 248, 623-652. c)
R. W. Hoffmann, B. Holzer, J. Chem. Soc.,
Chem. Commun. 2001,
491-492.
[2] a) R. R. Holmes, Pentacoordinated Phosphorus Structure and Spectroscopy, ACS
Monograph 175, American Chemical Society: Washington, DC, 1980, Vols. I and II;
b) R. R. Holmes, Acc. Chem. Res., 1998, 31, 535-542; c) A.
Arduengo, J. III; C. A. Stewart, Chem.
Rev., 1994, 94, 1215-1237; d) C. Y. Wong, D. K. Kennepohl, R. G. Cavell, Chem. Rev. 1996, 96, 1917-1951.
[3] For a recent work about hypervalent
pentacoordinate carbon compounds see: M. Yamashita, Y. Yamamoto, K. Akiba, D.
Hashizume, F. Iwasaki, N. Takagi, S. Nagase J.
Am. Chem. Soc. 2005, 127, 4354-4371 and references cited
therein.
[4] a) G. Baccolini, C. Boga, M. Galeotti,
Angew. Chem. 2004, 116, 3120-3122; Angew. Chem. Int. Ed. 2004,
43, 3058-3060. b) G. Baccolini, C. Boga, M. Mazzacurati, F. Sangirardi Org. Lett. 2006,
8, 1677-1680.
[5] Phosphorus-31
NMR Spectroscopy in Stereochemical Analysis, J. G. Verkade, and L. Quin, Eds.,
Methods in Stereochemical Analysis, VCH, Deerfield Beach, FL, 1987, Vol 8.
[6] H. Gilman, E. A. Zoellner, J. Am. Chem. Soc., 1929, 51, 3493-3496.
Tetrahedron
Volume 63, Issue 51, 17 December
2007, Pages 12595-12600
Carbon–phosphorus bond formation and transformation in the reaction of
1,2-diaza-1,3-butadienes with alkyl phenylphosphonites
Orazio A. Attanasi
a,
,
, Graziano Baccolinib, Carla Bogab, Lucia
De Crescentinia, , , Paolino
Filipponea and Fabio
Mantellinia
aIstituto
di Chimica Organica, Università degli Studi di Urbino ‘Carlo Bo’, Via I
Maggetti 24, 61029 Urbino, Italy
bDipartimento
di Chimica Organica ‘A. Mangini’, Università degli Studi di Bologna, Viale
Risorgimento 4, 40136 Bologna, Italy
Abstract
The reaction of 1,2-diaza-1,3-butadienes with dialkyl
phenylphosphonites under solvent-free conditions proceeds via zwitterionic
intermediate and gives, by precipitation, the stable ylidic 
-phosphanylidene-hydrazones
that, in turn, can be transformed into the corresponding 3-phenyl-2H-1,2,3λ5-diazaphospholes. The latter compounds are converted
by hydrolytic cleavage in methanol–water (95:5) into E-hydrazonophosphonates
that are useful for the preparation of the corresponding β-ketophosphonates and
4-[alkoxy(phenyl)phosphoryl]-1,2-diaza-1,3-butadienes. These peculiar
1,2-diaza-1,3-butadienes, bearing an alkoxy(phenyl)phosphoryl group on the
carbon atom in position 4 are also able to add different nucleophiles, such as
methanol or thiourea, giving 2-[alkoxy(phenyl)phosphoryl]-2-methoxyhydrazones and
5-phosphinate-substituted thiazol-4-ones, respectively.
Graphical abstract
Tetrahedron
Volume 64, Issue 28, 7 July 2008,
Pages 6724-6732
Reaction
of 1,2-Diaza-1,3-butadienes with Aminophosphorus Nucleophiles:
A
Practical Access to New Phosphorylated Pyrazolones
Orazio
A. Attanasi,*[a] Graziano Baccolini,[b] Carla Boga,[b] Lucia De
Crescentini,*[a]
Gianluca
Giorgi,[c] Fabio Mantellini,[a] and Simona Nicolini[a]
The reaction of 1,2-diaza-1,3-butadienes with dibenzyl
diisopropylphosphoramidite, methyl tetraisopropylphosphorodiamidite
or tris(dimethylamino)phosphane under solventfree conditions gave stable
α-phosphoranylidene-hydrazones
that, in turn, were transformed into the corresponding
5-oxo-4-phosphoranylidene-4,5-dihydro-1H-pyrazoles. X-ray diffraction
analysis of one of these derivatives is reported. α-
Phosphoranylidene-hydrazones, derived from the reactionbetween
1,2-diaza-1,3-butadienes with dibenzyl diisopropylphosphoramidite,
were converted by hydrolytic cleavageinto (E)-hydrazono-phosphonates,
which are useful for the preparation of the corresponding (3-oxo-2,3-dihydro-1H-pyrazol-4-yl)phosphonamidates.
E.J.O.C, 2008,5965
The First Flights of a Molecular Shuttle Transporting Elements: Easy
One-pot Formation of Organic Cyclic Arsanes, Stibanes and Bismutanes
Graziano Baccolini,*[a]
Carla Boga,*[a] Marzia Mazzacurati,[a] Gabriele
Micheletti[a]
New arsenic-, antimony-, and bismuth-donor
reagents (1b–d) are used in a
one-pot synthesis of cyclic arsanes, stibanes and bismutanes through a
procedure in which the simultaneous formation of three C–As, C–Sb, or C–Bi bonds is achieved. At the
end of the reaction, the element-donor reagent can be easily reformed ‘in situ’ and recycled, as in a catalytic
process.
Chemistry,
A European Journal December, 2009, 597- 599