CONVENIENT SYNTHESIS OF 2,3-DIHYDRO-1,2,4-THIADIAZOLES, 4,5-DIHYDRO-1,3-THIAZOLES, AND 1,3-THIAZOLES THROUGH A [4+1]-TYPE OXIDATIVE RING CLOSURE OF 1,3-THIAZA-1,3-BUTADIENES

摘要

1,3-Thiaza-1,3-butadienes bearing an N,N-dimethylamino group at the C-2 position were efficiently converted into 5H-1,2,4-oxathiazoles, 2,3-dihydro-1,2,4-thiadiazoles, 4,5-dihydro-1,3-thiazoles, and 1,3-thiazoles through an oxidative ring closure by treating with mCPBA, chloramine-T, metal carbenoids, or dichlorocarbene, respectively, via the ring closure of in situ generated heterocumulene-type reactive species involving thione S-oxides, thione S-imides, and thiocarbonyl ylides.