Synthesis of 3-alkyl- and 3-chloroalkyl-2-hydroxybenzoates based on [3+3] cyclizations of 4-alkyl- and 4-chloroalkyl-1,3-bis(trimethylsilyloxy)buta-1,3-dienes

The TiCl4-mediated [3+3] cyclization of 4-alkyl- and 4-chloroalkyl-1,3-bis(trimethylsilyloxy)buta-1,3-dienes with 3-silyl-alk-2-en-1-ones afforded 3-alkyl- and 3-chloroalkyl-2-hydroxybenzoates, respectively; the latter containing a remote chloride functionality. The TiCl4- and TiBr4-mediated [3+3] cyclization of 1,3-bis(trimethylsilyloxy)-4-chloroalkylbuta-1,3-dienes with 1,1-diacetylcyclopropane afforded salicylates containing two remote halide functionalities.