One-pot synthesis of a 1,2-diphospholide by double C-H deprotonation

Article abstract of DOI:10.1002/ejic.201500177

The relationship between phosphorus and carbon chemistry has been realized for many years. Phosphorus relatives of classical organic ligands (like cyclopentadienide, Cp^-) in which carbon atoms have been substituted for phosphorus atoms are important classes of organometallic ligands, which are relevant to catalysis. Often, however, a limit to applying the phosphorus counterparts is the low-yielding and circuitous nature of their synthesis. A case in point is the 1,2-diphospholide ligand framework, an important analogue of the cyclopentadienyl ligand, which has only been obtained from multistep syntheses. We report in this paper a high-yielding and direct route to this type of framework using a very simple approach. Treatment of MesPHLi (Mes = 2,4,6-trimethylphenyl) with Sb(NMe₂)₃ generates the 5,7-dimethyl-1,2-benzodiphosphol-1-ide anion (1), the first 1,2-diphospholide analogue of indenyl. Structural and NMR spectroscopic investigations suggest that this unique reaction, involving double C-H deprotonation of a CH₃ group of the Mes ligand, occurs through the rearrangement of a tetraphospha-1,4-diide anion. Almost "In-denyl": 5,7-Dimethyl-1,2-benzodiphosphol-1-ide (1), a species valence-isoelectronic with the indenyl anion, is simply prepared in a one-pot synthesis by treatment of MesPH₂ with nBuLi and Sb(NMe₂)₃. This transformation involves an unprecedented double C-H deprotonation of a CH₃ group by a redox-active main group base.

Full text of DOI:10.1002/ejic.201500177

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SHORT COMMUNICATION
DOI:10.1002/ejic.201500177
One-Pot Synthesis of a 1,2-Diphospholide by Double C–H
Deprotonation
Lily S. H. Dixon,[a] Peter D. Matthews,[a] Sophia A. Solomon,[a] and
Dominic S. Wright*[a]
Keywords: C–H deprotonation / Dehydrocoupling / 1,2-Diphospholide / Phosphorus / Phosphorus heterocycles
The relationship between phosphorus and carbon chemistry
has been realized for many years. Phosphorus relatives of
multistep syntheses. We report in this paper a high-yielding
and direct route to this type of framework using a very simple
classical organic ligands (like cyclopentadienide, Cp–) in approach. Treatment of MesPHLi (Mes = 2,4,6-trimeth-
which carbon atoms have been substituted for phosphorus
atoms are important classes of organometallic ligands, which
are relevant to catalysis. Often, however, a limit to applying
the phosphorus counterparts is the low-yielding and circu-
itous nature of their synthesis. A case in point is the 1,2-di-
phospholide ligand framework, an important analogue of the
cyclopentadienyl ligand, which has only been obtained from
ylphenyl) with Sb(NMe2)3 generates the 5,7-dimethyl-1,2-
benzodiphosphol-1-ide anion (1), the first 1,2-diphospholide
analogue of indenyl. Structural and NMR spectroscopic in-
vestigations suggest that this unique reaction, involving
double C–H deprotonation of a CH3 group of the Mes ligand,
occurs through the rearrangement of a tetraphospha-1,4-di-
ide anion.
Introduction
The ability to tune the steric and electronic character of
transition metal centers using different auxiliary ligand sets
is an important and central theme in organo-transition
metal chemistry and homogeneous catalysis.[1] For this
reason, there has been increasing interest in new types of
phosphorus-based ligands, particularly counterparts of
classical organic ligands in which some or all of the carbon
atoms are substituted for phosphorus atoms.[2] A de-
Scheme 1. General method for the preparation of oligophosphane-
diides. M = Na, K; R = tBu, Mes, Ph; n = 0, 1, 2; controlled by
varying R, x and y.
Recently, we have been interested in the use of main
group metals in the stoichiometric and catalytic dehy-
drocoupling of element–H bonds. Relevant to the current
study is work that has shown that treatment of primary
phosphanes (RPH2) with a redox-active superbase mixture
of n-butyllithium and E(NMe2)3 (E = As, Sb) results in the
ultimate formation of cyclic phosphanes [RP]4 and Zintl
ions.[7] Intermediates in these reactions are the heterocyclic
anions [(RP)nE]–, the size of which depends on the steric
demands of the R group (Scheme 2). In the sterically most
demanding case, Mes*PH2 (Mes* = 2,4,6-tri-tert-but-
veloping class of phosphorus ligands are the oligophos-
2– [3]
phanediides of the form [PR]n
.
These were first eluci-
dated in landmark studies by Issleib.[4] The general method
of synthesis (outlined in Scheme 1) has been used to pre-
pare a series of oligophosphanediides through the coupling
of dicholorophosphanes and subsequent reductive ring
opening by further equivalents of alkali metal, either in a
one- or two-step synthesis. More recent studies by Hey-
Hawkins and Grützmacher have explored the structural
properties and coordination chemistry of these com-
pounds.[5,6] However, aside from transmetallations of the al-
2–
kali metal salts of [PR]n with a range of transition and
main group metal precursors, yielding metallocyclic and
heterocyclic products in which the [RP]n backbone is main-
tained, little investigation into the reactivity of the oligo-
phosphanediides in their own right has been conducted.
[a] Department of Chemistry, University of Cambridge
Lensfield Rd, Cambridge CB2 1EW, UK
E-mail: dsw1000@cam.ac.uk
http://www.ch.cam.ac.uk/group/wright
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejic.201500177.
Scheme 2. Products generated on the treatment of various lithiated
primary phosphanes with As(NMe2)3 (L,LЈ = Lewis base ligand).
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SHORT COMMUNICATION
ylphenyl), the 1,3-diphospha-2-arsaallyl anion is produced,
which is valance-isoelectronic with the carbon-based allyl
anion.[8]
In studies initially aimed at extending this work to
MesPH2, we found that the (5,7-dimethyl-1,2-benzodiphos-
phol-1-ide anion, the first 1,2-phospholide homologue of
the indenyl ligand, can be obtained in a single, high-yielding
step from the reaction of MesPH2 (Mes = 2,4,6-trimeth-
ylphenyl) with nBuLi/Sb(NMe2)3. This reaction results
from base-induced rearrangement of a tetraphospha-1,4-di-
ide anion and is a unique example of double C–H depro-
tonation of a CH3 group in main group chemistry.
Results and Discussion
The one-pot synthesis of the 1,2-diphospholide anion 1
was achieved by treatment of MesPH2 with nBuLi/TMEDA
(2 equiv./4 equiv.), followed by addition of Sb(NMe2)3
(0.5 equiv.). The salt [Li(TMEDA)2][1] was isolated as a yel-
low solid in a yield of 72%, the reaction involves net oxid-
ation of the MesPH2 and reduction of SbIII. Although the
complex is also formed in a high yield using 2 equiv. of
TMEDA, the presence of an excess of the ligand avoids
contamination of the solid product by LiNMe2 (Scheme 3).
The complex [Li(TMEDA)2][1] was initially characterized
by 1H and 31P NMR spectroscopy. Diagnostic signals in the
Figure 1. Molecular structure of 5,7-dimethyl-1,2-benzodiphos-
phol-1-ide (1); the Li(TMEDA)2 counterion and all hydrogen
atoms [except H(1)] are omitted for clarity.
these synthetic methods, there are no known syntheses of
indenyl variants of 1,2-diphospholides, such as 1.
In situ 31P NMR spectroscopy was utilized to probe in-
termediates formed during the reaction (Figure 2). These
studies were carried out under the same conditions as in
Scheme 3, except that 1 equiv. of nBuLi and 2 equiv. of
TMEDA were used to deliberately limit the extent of reac-
tion. Immediately after mixing the reactants, a number of
intermediates can be identified, including the cyclic phos-
phanes cyclo-[MesP]3 (A1) and cyclo-[MesP]4 (A2) and the
1
2
31P NMR spectrum at δ = 221.3 (dd, JPP = 447, JPH
=
1
38 Hz, 1 P) and 131.0 (d, JPP = 447 Hz, 1P) ppm and in
1
2
the H NMR spectrum at δ = 7.89 (d, JPH = 38 Hz, 1 H)
ppm were strongly indicative of double C–H deprotonation
of an ortho-methyl group and the formation of a carbon–
phosphorus double bond (for spectra see the Supporting
Information, Figures S1 and S2).
2–
tetraphospha-1,4-diide [MesP]4 (B) (Figure 2a).[12] After
heating to reflux for 1 h, the spectrum shows the formation
of 1 and the build-up of an unidentified intermediate (C)
characterized by doublets at δ = 89.4 and –101.6 (1JPP
=
347 Hz) (Figure 2b) (see also Scheme 5). Extended heating
of this reaction mixture led to no further reaction. However,
Scheme 3. Method for the synthesis of the 5,7-dimethyl-1,2-benzo-
diphosphol-1-ide anion (1). Complete conversion to 1 was observed
by in situ 31P NMR spectroscopy. Toluene solvent, (i) stirred at
room temp. for 1 h, (ii) stirred at room temp. for 30 min, then
heated under reflux for 1 h.
Further confirmation of the structure of 1 was provided
by X-ray analysis (Figure 1). This allowed unequivocal as-
signment of atom connectivity; however, the poor quality
of the data obtained renders an in depth discussion of bond
lengths and angles meaningless.[9]
In comparison to this simple one-pot route, the few ex-
amples of the synthesis of 1,2-diphospholides found in the
literature involve multistep syntheses, make use of highly
hazardous reagents (white phosphorus, sodium metal) or
are low-yielding.[10,11] A case in point is the 3,4,5-triphenyl-
1,2-diphosphacyclopentadienide anion, [(PhC)3P2]–, which
has only been obtained by the reaction of an organometallic
Figure 2. (a) 31P NMR spectrum of the reaction residue obtained
immediately after addition of 0.5 equiv. of Sb(NMe2)3;[12] (b) in situ
31P{1H} NMR spectrum of the reaction mixture prepared after
heating under reflux for 1 h; (c) in situ 31P{1H} NMR spectrum of
the reaction mixture with a further 0.5 equiv. of Sb(NMe2)3 added
and stirred at room temp. for 16 h. The region δ = –10 to 85 ppm
–
cyclopropenylium–NiII complex with the P5 anion.[10] It is
also worthwhile noting that due to the lack of generality of (which shows no other species) has been omitted.
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SHORT COMMUNICATION
2–
addition of further equivalents of base [Sb(NMe2)3 or [MesP]4 anion (B) is the precursor to 1 and that conver-
nBuLi/TMEDA] led to near quantitative conversion into 1 sion from B to 1 is base-activated.[15]
(Figure 2c), illustrating that the transformation of C to 1 is
base-induced.
A series of reactions was investigated using the reagent
As(NMe2)3 in place of Sb(NMe2)3, reasoning that the
slower rates of the reactions, resulting from the lower basic-
ity of the base, would allow us to deduce the order in which
key intermediates are formed. Using the same stoichio-
metry and reaction conditions that were employed in the
previous NMR spectroscopic study of the Sb system pro-
duced a final mixture composed of 1 and a new mixed As–P
heterocycle (2) (Scheme 4).[13] The crystalline solid obtained
from storage at 4 °C was found to have a bulk composition
of [Li(TMEDA)2][1]0.6[2]0.4 based on 31P and 1H NMR
analyses (see the Supporting Information, Figures S4 and
S5). The identity of 2 is further supported by X-ray analysis
of a single crystal, which showed this to be the co-complex
Figure 3. (a) 31P NMR spectrum of a B/2 mixture in [D8]THF. (b)
[Li(TMEDA)2][1]0.25[2]0.75 (see the Supporting Information,
31P NMR spectrum following treatment of the B/2 mixture in tolu-
Figure S6). We assume that the absence of the antimony-
based analogue of 2 in the reaction with Sb(NMe2)3 is due
to its instability. We were also able to identify the previously
reported Zintl compound [As7(Li·TMEDA)3] in the reac-
tion mixture (see the Supporting Information, Figure S7).
The isolation of this Zintl compound is consistent with the
overall oxidation of MesPH2 to 1 and 2 in the reaction (i.e.,
ene with TMEDA (2 equiv.) and nBuLi (1 equiv.) and refluxing for
1 h ([D8]THF).
3–
with accompanying reduction of AsIII to the As7 ion).
Scheme 4. Products isolated from reaction of MesPH2 with nBuLi/
2TMEDA and As(NMe2)3. Toluene solvent, (i) stirred at room
temp. for 1 h, (ii) stirred at room temp. for 30 min, then heated
under reflux for 1 h.
Figure 4. Molecular structure of the singly chelated tetraphospha-
1,4-diide, [Li(TMEDA)(MesP)4]–; hydrogen atoms and the
[Li(TMEDA)2]+ counterion are omitted for clarity.[16]
Drawing together the observations made from both reac-
tion systems involving Sb(NMe2)3 and As(NMe2)3, allows
the mapping of a partial mechanism for the reaction pro-
The 31P NMR spectrum of the reaction obtained after ducing the diphospholide 1 (Scheme 5). The formation of
initial mixing of the reagents and brief heating shows the cyclic phosphanes {[MesP]3 (A1) and [MesP]4 (A2)} ob-
presence of the cyclic phosphanes [MesP]3 (A1) and served at the early stage of the reaction (STEP 1) is under-
[MesP]4 (A2) (see the Supporting Information, Figure S8).
standable in terms of previous work in this area, which has
After stirring at ambient temperature for 30 min, only shown that a range of aliphatic and aromatic phosphanes
[MesP]42– (B) and the P/As heterocycle 2 are observed (Fig- undergo similar dehydrocoupling to cyclic phosphanes in
ure 3a). The formation of B was confirmed by X-ray analy- the presence of E(NMe2)3/nBuLi, an oxidative coupling re-
sis of the crystalline complex [{Li(TMEDA)2}- action that is accompanied by the reduction of E(NMe2)3
{(MesP)4Li(TMEDA)}] grown from this solution (Fig- to Zintl compounds (E73–).[7] STEP 2 involves the reductive
ure 4).[14] The addition of nBuLi (ca. 0.5 equiv.) and ring opening of A1 and A2 forming the tetraphospha-1,4-
2–
TMEDA (ca. 1 equiv.) to the mixture of B and 2 followed diide [MesP]4 (B). This process is well established for al-
by heating under reflux for 1 h gave near complete conver- kali metals, but is likely to be due here to the presence of
sion to 1 and 2 (Figure 3b). This illustrates that the the highly reducing Zintl ions in this system. What is strik-
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SHORT COMMUNICATION
–78 °C and treated with 1.6 m n-butyllithium in hexane (2.0 mL,
3.2 mmol). The resultant yellow solution was warmed to room
temp. and stirred for a further 1 h to give an orange suspension of
MesPHLi. This suspension was cooled again to –78 °C and treated
with 2.0 m Sb(NMe2)3 in toluene (0.36 mL, 0.7 mmol) before being
warmed to room temp. The now brown/black suspension was
stirred for 30 min before being heated under reflux for 1 h. The
volume of the reaction was reduced in vacuo to ca. 4 mL and the
resultant mixture stored at –15 °C overnight. Crystals of
Li(TMEDA)2[1] were isolated by filtration, before being washed
ing about the proceeding reaction of B is that it exclusively
yields the 1,2-diphospholide 1, showing that both of the P2
“halves” of B convert to 1. A schematic for this conversion
is shown in STEP 3 and STEP 4, both of which are base-
induced. An interesting possibility is that the net reduction
occurring in these steps (– 2 e–, STEP 3) could be coupled
to the oxidation in the previous step (+ 2 e–, STEP 2),
3–
through oxidative and reduction of E7 Zintl ions.[17] The
2–
absence of a signal arising from [MesP]2 in the 31P NMR
spectrum shown in Figure 3(b) suggests that if this species with n-pentane (10 mL). The finely divided, almost colloidal Sb
metal present does not settle and is removed with the washing sol-
vent at this stage. The remaining yellow solid was dried under re-
duced pressure. Yield 0.21 g (72%). 1H NMR (500 MHz, [D8]
is formed during STEP 3, it is short-lived and undergoes
conversion to 1. The observed insertion of a phosphorus
atom involved in the transformation of MesPH2 to 1 is rem-
iniscent of the formation of the 1,2,3-triphospholide
[C6H4P3]– from 1,2-(PH2)2C6H4.[18] However, the mecha-
nism of formation of 1 is clearly different from the triphos-
pholide analogue and does not involve the sacrifice of a
phosphorus-containing by-product.
2
THF): δ = 7.92 [d, JPH = 38 Hz, 1 H, P(CH)C], 7.34 [s, 1 H,
C(CH)C], 6.32 [s, 1 H, C(CH)C], 2.64 (s, 3 H, CH3, A ), 2.33 (s, 8
H, CH2, TMEDA), 2.33 (s, 3 H, CH3, A), 2.18 (s, 24 H, CH3,
TMEDA)
ppm.
31P
NMR
(202 MHz,
1
2
[D8]THF): δ = 222.0 (dd, JPP = 448, JPH = 38 Hz, 1 P, PPCH),
1
132.1 (d, JPP = 448 Hz, 1 P, PPCH) ppm.
Acknowledgments
We thank the Cambridge International European and
Commmonwealth Trust (L. S. H. D.), the European Union (EU)
(ERC Advanced Grant, D. S. W., S. A. S.) and the Engineering and
Physical Sciences Research Council (EPSRC) (P. D. M.) for finan-
cial support and Dr. J. E. Davies for collecting X-ray data.
[1] J. P. Collman, L. S. Hegedus, J. R. Norton, R. C. Finke, Prin-
ciples and Applications of Organotransition Metal Chemistry,
Oxford University Press, Mill Valley, California, 1987; J. Hart-
wig, Organotransition Metal Chemistry – From Bonding to Ca-
talysis, University Science Books, Mill Valley, California, 2010.
[2] K. B. Dillon, F. Mathey, J. F. Nixon, Phosphorus – The Carbon
Copy, John Wiley & Sons, Chichester, 1998.
Scheme 5. Proposed schematic for the formation of 1 from
MesPH2.
[3] M. Baudler, Angew. Chem. Int. Ed. Engl. 1987, 26, 419–441;
Angew. Chem. 1987, 99, 429.
[4] K. Issleib, K. Krech, Chem. Ber. 1965, 98, 2545–2550; K.
Issleib, M. Hoffman, Chem. Ber. 1966, 99, 1320–1324.
[5] R. Wolf, A. Schisler, P. Lönnecke, C. Jones, E. Hey-Hawkins,
Eur. J. Inorg. Chem. 2004, 3277–3286; S. Gómez-Ruiz, E. Hey-
Hawkins, Coord. Chem. Rev. 2011, 255, 1360–1386.
[6] D. Stein, A. Dransfeld, M. Flock, H. Rüegger, H.
Grützmacher, Eur. J. Inorg. Chem. 2006, 4157–4167.
[7] M. A. Beswick, N. Choi, A. D. Hopkins, M. Mcpartlin,
M. E. G. Mosquera, R. Paul, A. Rothenberger, D. Stalke, J.
Wheatley, D. S. Wright, Chem. Commun. 1998, 49, 2485–2486;
R. J. Less, R. L. Melen, V. Naseri, D. S. Wright, Chem. Com-
mun. 2009, 4929–4937.
Conclusions
A novel 1,2-diphospholide, 1, analogous to the indenyl
anion, is formed in a high-yielding, one-pot reaction di-
rectly from MesPH2. Detailed NMR spectroscopic and
structural investigations show that the formation of 1 in-
volves based-initiated rearrangement of a tetraphospha-1,4-
diide anion. The deprotonation of two H atoms of the or-
tho-methyl group of MesPH2 to give 1 can be regarded as
a double C–H/P–H dehydrocoupling reaction and is un-
precedented for a main group reagent. Further studies are
underway to extend this work to intermolecular P–C bond
formation and to a range of other difficult to prepare het-
erocyclic systems.
[8] L. S. H. Dixon, L. K. Allen, R. J. Less, D. S. Wright, Chem.
Commun. 2014, 50, 3007–3009.
[9] Crystal data: [Li(TMEDA)2][1], C21H41Li1N4P2, M = 418.46,
¯
triclinic, space group P1, Z = 6, a = 16.5529(8), b = 16.7980(8),
c = 17.6254(9) Å, α = 68.605(2), β = 69.828(2), γ = 61.803(2)°,
V
=
3931.8(3) Å3, μ(Cu-Kα)
=
1.582 mm–1, ρcalcd.
=
1.060 Mgm–3, T = 180(2) K. Total reflections 27302, unique
5699 (Rint = 0.0317). R1 = 0.0864 [IϾ2σ(I)] and wR2 = 0.2440
(all data). Data were refined by full-matrix least squares on F2
(G. M. Sheldrick, SHELX-2014/6, Göttingen, 2014). CCDC-
1037634 contains the supplementary crystallographic data for
[Li(TMEDA)2][1]. These data can be obtained free of charge
from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
Experimental Section
Synthesis of Li(TMEDA)2[1]: The synthesis and all manipulations
were carried out under dry, O2-free nitrogen and in anhydrous, de-
gassed solvents. A solution of MesPH2 (0.22 g, 1.4 mmol) and
TMEDA (0.87 mL, 5.8 mmol) in toluene (7 mL) was cooled to
[10] V. Miluykov, A. Kataev, O. Sinyashin, P. Lo, P. Lönneche, E.
Hey-Hawkins, Organometallics 2005, 24, 2233–2236.
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SHORT COMMUNICATION
[11] N. Maigrot, N. Avarvari, C. Charrier, F. Mathey, Angew. Chem.
Int. Ed. Engl. 1995, 34, 590–592; Angew. Chem. 1995, 107, 623.
[12] In order to halt the reaction immediately, solvent was removed
after addition of Sb(NMe2)3 and the solid residue washed with
n-pentane, removing nBuLi and TMEDA. The 31P{1H} NMR
spectrum of the n-pentane washings shows the presence of the
cyclic phosphanes A1 and A2 (see the Supporting Information,
Figure S3).
[13] The mechanism of formation of 2 is not understood at this
stage; however, 31P NMR studies suggest that the tetraphos-
pha-1,4-diide B is also the immediate precursor (see the Sup-
porting Information, Figures S9 and S10).
Z = 2, a = 16.1229(7), b = 12.2196(6), c = 17.0599(8) Å, α =
90, β = 102.869(2), γ = 90°, V = 3276.6(3) Å3, μ(Mo-Kα) =
0.154 mm–1, ρcalcd. = 1.070 Mgm–3, T = 240(2) K. Total reflec-
tions 15328, unique 4215 (Rint = 0.0529). R1 = 0.0947
[IϾ2σ(I)] and wR2 = 0.2772 (all data). Data were refined by
full matrix least-squares on F2 (G. M. Sheldrick, SHELX-97,
Göttingen, 1997). CCDC-1037635 contains the supplementary
crystallographic data for [Li(TMEDA)2][(MesP)4·Li(TMEDA)]·
(C7H8). These data can be obtained free of charge
from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif. This structure is similar
2–
to those reported previously containing [RP]4 anions (see
[14] After addition of As(NMe2)3, the reaction mixture was stirred
ref.[5,6]).
at room temp. for 30 min, before being stored at 4 °C for 5 d [17] S. Scharfe, F. Kraus, S. Stegmaier, A. Schier, T. F. Fässler, An-
to afford
[As7][Li·TMEDA]3.
a
batch of crystals containing B,
2
and
gew. Chem. Int. Ed. 2011, 50, 3630; Angew. Chem. 2011, 123,
3712.
[15] Conversion to the neutral cyclic phosphanes A1 and A2 is ob-
served on heating the B/2 mixture to reflux in toluene for 1 h
in the absence of base, suggesting that the reductive ring open-
ing from A1/A2 to B is reversible under the reaction conditions.
[16] Crystal data: [Li(TMEDA)2][(MesP)4·Li(TMEDA)]·(C7H8),
C61H100Li2N6P4, M = 1055.23, monoclinic, space group P2/n,
[18] R. Edge, R. J. Less, V. Naseri, E. J. L. McInnes, R. E. Mulvey,
D. S. Wright, Dalton Trans. 2008, 6454–6460; F. García, R. J.
Less, V. Naseri, M. McPartlin, J. M. Rawson, M. San-
cho Tomas, D. S. Wright, Chem. Commun. 2008, 859–861.
Received: February 19, 2015
Published Online: ᭿
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SHORT COMMUNICATION
Diphospholides
L. S. H. Dixon, P. D. Matthews,
S. A. Solomon, D. S. Wright* ........... 1–6
Almost “In-denyl”: 5,7-Dimethyl-1,2-
benzodiphosphol-1-ide (1), a species va-
lence-isoelectronic with the indenyl anion,
is simply prepared in a one-pot synthesis
by treatment of MesPH2 with nBuLi and
Sb(NMe2)3. This transformation involves
an unprecedented double C–H depro-
tonation of a CH3 group by a redox-active
main group base.
One-Pot Synthesis of a 1,2-Diphospholide
by Double C–H Deprotonation
Keywords: C–H deprotonation / Dehydro-
coupling
/ 1,2-Diphospholide / Phos-
phorus / Phosphorus heterocycles
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