ZUSCHRIFTEN Angew. Chem. 2000, 112, Nr. 18  WILEY-VCH Verlag GmbH, D-69451 Weinheim, 2000 0044-8249/00/11218-3457 $ 17.50+.50/0 3457 Synthesis, Structure, and Reactivity of a1s 4 ,3s 2 -Diphosphaallene** Tsuyoshi Kato, Heinz Gornitzka, Antoine Baceiredo, and Guy Bertrand* Among the possible heterocumulenes featuring the PCP sequence, 1s 4 ,3s 4 -diphosphaallenes (carbodiphosphoranes) A [1] and 1s 2 ,3s 2 -diphosphaallenes B [2] have been known for many years. Here we report the synthesis of a 1s 4 ,3s 2 - diphosphaallene C. Such a highly functionalized molecule (two different types of phosphorus carbon ªdoubleº bond and a lone pair at one of the phosphorus atoms) has only been postulated as an intermediate, but never observed spectro- scopically. [3] Our synthetic strategy was based on two consecutive rearrangements: the well-established 1,2-migration reaction of singlet carbenes, [4] which operates for phosphinocarbenes [Eq. (1)], [5] and the 1,2-halogen shift associated with a- halogenophosphanes [Eq. (3)]. [6] Combining these two 1,2- migration reactions, a possible precursor for the preparation of the desired 1s 4 ,3s 2 -diphosphaallene can be identified as the (phosphino)(chlorophosphino)diazomethane of type D [Eq. (2)]. Exactly this type of derivative, namely [bis(diisopropyl- amino)phosphino][chloro(diisopropylamino)phosphino]diazo- methane (1), is readily available in one step by addition of the lithium salt of [bis(diisopropylamino)phosphino]diazome- thane [7] to dichloro(diisopropylamino)phosphane (Scheme 1). Scheme 1. [12] D. A. Evans, A. H. Hoveyda, J. Am. Chem. Soc. 1990, 112, 6447. [13] Our preliminary work was performed with the benzyl instead of the PMB ether in 17 (ref. [3c]), but this could not be deprotected satisfactorily on the solid support. [14] a) S. D. Rychnovsky, D. Skalitzky, Tetrahedron Lett. 1990, 31, 945; b) D. A. Evans, D. L. Rieger, J. R. Gage, Tetrahedron Lett. 1990, 31, 7099; c) S. D. Rychnovsky, B. Rogers, G. Yang, J. Org. Chem. 1993, 58, 3511. [15] K. Horita, T. Yoshioka, T. Tanaka, Y. Oikawa, O. Yonemitsu, Tetrahedron 1986, 42, 3021. [16] a) J. R. Parikh, W. von E. Doering, J. Am. Chem. Soc. 1967 , 89, 5505; b) C. Chen, L. A. Ahlberg Randall, B. R. Miller, A. D. Jones, M. J. Kurth, J. Am. Chem. Soc. 1994, 116, 2661. [17] The stereochemistry was established using the methods described previously (ref. [3d]). 25 :[a] 25 D  1.8 (c  0.87, CHCl 3 ); IR (thin film): n Ä  3442, 3019, 1513, 1466, 1383, 1248 cm 1 ; 1 H NMR (500 MHz, CDCl 3 ): d  7.28 (d, J  8.6 Hz, 2 H), 6.87 (d, J  8.6 Hz, 2H), 4.78 (s, 1 H), 4.46 (ABq, 2 H), 4.13 (s br, 1 H), 3.80 (s, 3 H), 3.76 ± 3.72 (m, 3 H), 3.64 (t, J  5.9 Hz, 2 H), 3.58 (dd, J  8.7, 6.9 Hz, 1H), 3.53 (td, J  8.7, 1.9 Hz, 1H), 3.37 (dd, J  8.7, 6.9 Hz, 1H), 2.10 (s br, 1H), 2.00 ± 1.95 (m, 2 H), 1.84 ± 1.79 (m, 1 H), 1.75 ± 1.55 (m, 5H), 1.48 (s, 3H), 1.37 (s, 3 H), 0.93 (d, J  7.1 Hz, 3H), 0.90 (d, J  6.8 Hz, 3 H), 0.77 (d, J  6.6 Hz, 3 H), 0.72 (d, J  6.8 Hz, 3 H) ; 13 C NMR (100.6 MHz, CDCl 3 ): d  159.0, 131.0, 129.2, 113.7, 98.3, 83.4, 81.0, 76.0, 74.3, 72.9, 63.0, 55.3, 38.1, 35.9, 34.9, 34.1, 29.9, 29.6, 28.4, 19.8, 13.1, 11.8, 9.4, 4.8; HRMS (CI): calcd for C 27 H 47 O 7 [MH  ] 483.3322; found: 483.3321. 28 : [a] 25 D  5.6 (c  1.06, CHCl 3 ); IR (thin film): n Ä  3415, 2934, 1709, 1611, 1513, 1458 cm 1 ; 1 H NMR (400 MHz, CDCl 3 ): d  7.20 (d, J  8.7 Hz, 2 H), 6.85 (d, J  8.7 Hz, 2 H), 4.39 (ABq, 2 H), 4.20 (dd, J  9.7, 2.3 Hz, 1 H), 3.79 (s, 3 H), 3.82 ± 3.78 (m, 1 H), 3.65 (t, J  8.9 Hz, 1 H), 3.65 ± 3.60 (m, 2 H), 3.38 (dd, J  8.9, 4.6 Hz, 1 H), 3.23 (td, J  7.5, 2.5 Hz, 1 H), 3.10 (m, 1 H), 2.82 (m, 1 H), 2.69 (d, J  4.7 Hz, 1 H), 2.34 (s br, 1H), 1.75 ± 1.50 (m, 6H), 1.32 (s, 3H), 1.25 (s, 3H), 1.03 (d, J  7.1 Hz, 3H), 1.00 (d, J  7.3 Hz, 3H), 0.86 (d, J  6.7 Hz, 3 H), 0.77 (d, J  6.8 Hz, 3 H) ; 13 C NMR (100.6 MHz, CDCl 3 ): d  217.5, 159.3, 129.6, 129.3, 113.8, 101.0, 75.5, 73.0, 72.2, 70.3, 69.1, 62.7, 55.2, 50.5, 44.3, 38.4, 33.8, 31.5, 29.7, 24.8, 23.7, 14.2, 12.8, 11.7, 7.9; HRMS [ES  ]: calcd for C 27 H 44 O 7 Na [M  Na] 503.2973; found: 503.2963. [18] I. Paterson, M. A. Lister, Tetrahedron Lett. 1988, 29, 585. [19] Attempted anti reduction using Me 4 NBH(OAc) 3 in THF/AcOH led only to modest diastereoselectivity after cleavage (75 % ds). D. A. Evans, K. T. Chapman, E. M. Carreira, J. Am. Chem. Soc. 1988, 110, 3560. [20] The syn ± syn-aldol adduct using (R)-4a can be obtained by using either ()-Ipc 2 BOTf or Sn(OTf) 2 . I. Paterson, R. D. Tillyer, Tetrahe- dron Lett. 1992, 33, 4233. [21] Prepared from methyl (R)-3-hydroxy-2-methylpropionate by analogy with the procedures described previously: a) I. Paterson, R. D. Tillyer, J. Org. Chem. 1993, 58, 4182; b) I. Paterson, M. D. McLeod, Tetrahedron Lett. 1997 , 38, 4183. [*] Dr. G. Bertrand, T. Kato, Dr. H. Gornitzka, Dr. A. Baceiredo Laboratoire dHe Âte Ârochimie Fondamentale et Applique Âe Universite  Paul Sabatier 118, route de Narbonne, 31062 Toulouse cedex O4 (France) Fax: ( 33) 5-61-55-82-04 E-mail: gbertran@ramses.ups-tlse.fr [**] We are grateful to the French Embassy in Japan for a grant to T.K., and to the CNRS for financial support of this work.