Phosphinocarbenes Phosphino carbenes, reactivity

The (phosphino)(silyl)carbene 2a has been shown to exhibit this diagnostic reactivity. Under rather drastic conditions (300°C, 10 2 mm Hg), 2a has been converted into the azaphospholidine 37, in high yield, as a mixture of four diastereomers, which result from the presence of three asymmetric centers.4 The high regioselectivity of the carbene insertion (no formation of a four-membered ring was detected) is intriguing, especially since the same regioselectivity is observed upon thermolysis of bis(diisopropyl-amino)phosphinodiazomethane li.4 Yet, in contrast, four-membered heterocycles were obtained with other phosphinocarbenes (Sections V,C,1 and 3). 

This is the second type of stable phosphinocarbene to have been reported. In contrast to (phosphino)(silyl)carbenes, very little is known concerning their reactivity. No simple reactions typical of a carbene-like behavior have been reported. However, the reactivity at the periphery of the carbene center makes these derivatives powerful building blocks for novel compounds. 

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