Synthetic Applications of <i>o-</i> and <i>p</i>-Halobenzyl Sulfones as Zwitterionic Synthons: Preparation of <i>O</i><i>rtho-</i>Substituted Cinnamates and Biarylacetic Acids
作者:Ana Costa、Carmen Nájera、José M. Sansano
DOI:10.1021/jo025620s
日期:2002.7.1
The synthetic applications of o-halobenzyl and p-halobenzyl sulfones as precursors of 1,3- and 1,5-zwitterionic synthons, respectively, are described. Their alpha-sulfonyl carbanions, generated by means of the phosphazene base P-2-Et or BuLi or K2CO3 under PTC conditions, reacted with different electrophiles such as alkyl halides, aldehydes, and electrophilic olefins. Palladium-catalyzed cross-coupling processes such as Heck, Suzuki, and Sonogashira reactions can be efficiently performed at the halogen atom. These two sequential functionalization processes are applied to the synthesis of ortho-substituted cinnamates and pharmaceuticals belonging to the family of p-biarylacetic acids such as 4-biphenylacetic acid, namoxyrate, xenyhexenic acid, and bipherylpropionic acid.