75424-92-9Relevant articles and documents
REACTION OF 1-BENZOPYRYLIUM SALTS WITH TRIALKYL PHOSPHITE: FORMATION OF 2,4-DISUBSTITUTED 1-BENZOPYRAN DERIVATIVES
Iwasaki, Hideharu,Akiba, Kin-ya
, p. 2857 - 2860 (2007/10/02)
Reaction of 1-benzopyrylium perchlorate (1) with triethyl phosphite gave 2H-benzopyran-2-phosphonate (2) in good yield.Deprotonation of 2 with sec-BuLi at -78 deg C foolowed by addition of aromatic aldehydes gave exomethylene compound (4).Reaction of ketene solyl acetal (7) with 2-substituted 1-benzopyrylium salt (6), generated in situ from 4 by addition of CF3SO3H, afforded the corresponding 2,4-disubstituted 1-benzopyran (8).