Reactions of ylides formed from trialkyl phosphites with dialkyl acetylenedicarboxylates in the presence of carbon dioxide

Abstract

The ylides (2)⇌(3) formed from trialkyl phosphites and dialkyl acetylenedicarboxylates in the presence of carbon dioxide react with proton donors, such as phenol or diethylamine, to give stabilised ylides (4). With water, proton transfer within the stabilised ylide results in the formation of a quasiphosphonium salt (6) which can then cyclise to a 1,2-oxaphospholane (7) or dealkylate to give phosphonates (5). In some cases, hydrolysis of the ylide (2)⇌(3) occurs to give phosphate and an acid (9). The formation of a furan (12) during the reaction of the ylide (2)⇌(3) with 4-nitrobenzaldehyde has been investigated.