Exploring organic reactions using simple cyclodiphosphazanes

Abstract

Phosphine-activated reactions of alkynes/alkenes/allenes as well as the Mitsunobu reaction involve a rich phosphorus chemistry. With the aid of simple cyclodiphosphazanes, characterization of many compounds analogous to the proposed intermediates in such reactions has been accomplished. Use of a cyclodiphosphazane in Pd-catalyzed N-arylation reactions is highlighted. Results on molecular non-stoichiometry in phosphorus compounds and on the use of chiral phosphorus systems are discussed. Synthesis of allenylphosphoramides involving a cyclodiphosphazane is also described. X-ray structures of the new compounds [(t-BuNH)(PhCH₂CH(CN)CH₂-)P(μ-N-t-Bu)₂P(NH-t-Bu)]⁺[HCO₃]^- (13), [(t-BuNH)P(μ-N-t-Bu)₂P(=N-t-Bu)-C(=CH₂)CH(C₆H₄-4-Me)-P(O)(OCH₂CMe₂CH₂O)] (18), [(i-PrNH)P(μ-N-t-Bu)₂P(=N-i-Pr)-N(CO₂-i-Pr)-NH(CO₂-i-Pr)] (24), [(S)-(2-OH-1-C₁₀H₆-1'-C₁₀H₆-2'-O-P(O)(NH-t-Bu)₂] (36) and [(t-BuNH)(O)P(μ-N-t-Bu)₂P(O)(CH=C=CMe₂)] (40) are also reported.