Synthesis of 4-Alkyl- and 4-(ω-Chloroalkyl)-3-hydroxy-5-alkylidenebutenolides Based On Cyclizations of 4-Alkyl- and 4-(ω-Chloroalkyl)-1,3-bis(trimethylsilyloxy)buta-1,3-dienes with Oxalyl Chloride
4-Alkyl- and 4-(ω-chloroalkyl)-1,3-bis(trimethylsilyloxy)buta-1,3-dienes were prepared from ethyl acetoacetate in three steps. Their cyclization with oxalyl chloride allowed an efficient synthesis of 4-alkyl- and 4-(ω-chloroalkyl)-5-alkylidenebutenolides.