Diazoalkanes phosphaalkynes

Reaction of the amino-substituted phosphaalkyne Pr 2N-C=P with diazoalkanes 23a-23c as 1,3-dipolar reagents took place in toluene solution at ambient temperature with evolution of N2 and elimination of diisopropyl cyanamide. After 3-5 h bicyclic diphosphiranes 24a-24c were isolated. While solutions of 24a and 24c were stable, the mixture of diastereoisomers 24b decomposed in toluene (Scheme 8). 

The availability of phosphaalkenes R1P=CR22 and phosphaalkynes RC=P has led to the development of another route to phosphiranes and phosphirenes involving the formal addition of carbenes to phosphorus-carbon multiple bonds. When using diazoalkanes as the carbene source, the reaction mechanism involves the series of steps demonstrated by Niecke and co-workers in Scheme 23 <8iAG(E)i3i, 83CC1171) see also <75AG(E)363>. 

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