Cyclodiphosph(III)azane chemistry - Ylides from the reaction of [(RNH)P-N(t-Bu)] < inf > 2 < /inf > [R = t-Bu, i-Pr] with dimethyl maleate and chiral ansa-type derivatives from reaction of [ClP-N(t-Bu)] < inf > 2 < /inf > with a substituted BINOL

Abstract

Use of a simple inorganic ring system with the cyclodiphosph(III)azane skeleton [e.g. [(RNH)P-N(t-Bu)]2 [R = t-Bu (7), i-Pr (8)] to probe some of the intermediates proposed in phosphine mediated organic reactions is highlighted. Thus the reaction of 7-8 with the allenylphosphine oxide Ph 2P(O)C(Ph)CCH2 (9) affords the phosphinimines [(RNH)P(μ-N-t-Bu)2P(N-R)-C(CH2)CH(Ph)-P(O)Ph 2] [R = t-Bu (10), i-Pr (11)], while a similar reaction of 7-8 with dimethyl maleate (or dimethyl fumarate) affords the ylides [(RNH)P(μ-N-t-Bu) 2P(NH-R)C(CO2Me)-CH2(CO2Me) [R = t-Bu (18), i-Pr (19)]. The implication of such reactions on phosphine mediated organic transformations including Morita-Baylis-Hillman reaction is mentioned. In a rather rare type of situation, an unusually long phosphoryl (PO) bond [1.538 (5) ] as revealed the X-ray structure of {(R)-6,6′-(t-Bu) 2-1,1′-(C10H5)2-2,2′- O2-}{P(O)(N-t-Bu)2-P(Se)} (27) is rationalized by means of crystallographic disorder in packing after comparing the data with that in the literature and {1,1′-(C10H6)2-2,2′- O2}{P(Se)(N-t-Bu)2-P(Se)} (29). X-ray structures of the new compounds 10-11, 18-19, 27 and 29 are discussed. Compound 10 crystallizes in the chiral space group Pca2(1) with (S)-chirality at the carbon center [-C(CH2)CH(Ph)-P] suggesting a case of spontaneous resolution through crystallization. © 2011 Elsevier B.V. All rights reserved.