Organophosphorverbindungen, 73. Der Tri‐ tert ‐butyl‐2‐cyclopropen‐1‐yl‐Rest als kinetisch stabilisierende Gruppe für 1‐Aza‐3‐phosphaallene

Organophosphorus Compounds, 73 [1] . – The Tri‐ tert ‐butyl‐2‐cyclopropen‐1‐yl Substituent as Kinetically Stabilizing Group for 1‐Aza‐3‐phosphaallenes [2] The cyclopropenylphosphane 5 reacts with the isocyanates 6a–g to form the phosphaalkenes 7a–g . An analogous transformation occurs with the same phosphane and the bifunctional isocyanates 8a, b (→ 9a, b) . In contrast, the reaction 5 + 6h ends at the stage of the tautomers 11h ⇆ 12h . Methanolysis of 7b and of 11h ⇆ 12h leads to the carbamoyl‐cyclopropenylphosphanes 14a and b , respectively. Sodium hydroxide‐catalyzed elimination of hexamethyldisiloxane from 7b, g and the tautomer mixture 11h ⇆ 12h yields the target 1‐aza‐3‐phosphaallenes 16a–c .