Trifunctionalized allenes. Part III. Electrophilic cyclization and cycloisomerization of 4-phosphorylated 5-hydroxypenta-2,3-dienoates: An expedient synthetic method to construct 2,5-dihydro-1,2-oxaphospholes, furan-2(5H)-ones and 2,5-dihydrofurans

摘要

This chapter discusses the reactions of 4-phosphorylated 5-hydroxypenta-2,3-dienoates with protected or unprotected hydroxy group involving 5-endo-trig cyclizations. Reactions with electrophiles produce mixtures of the 2,5-dihydro-1,2-oxaphosphole-5-carboxylates and the 5-phosphoryl-furan-2(5H)-ones by competitive electrophilic cyclization due to the neighboring phosphonate (phosphine oxide) and the carboxylate groups participation. 4-Phosphorylated 5-hydroxypenta-2,3-dienoates were smoothly converted into the corresponding 4-phosphoryl-2,5-dihydrofuran-2-carboxylates by using 5 mol% of a silver salt as a catalyst in the 5-endo-trig cycloisomerization reaction.