Methyl α-acyloxy-γ-methylene-β-tetronate. Preparation and use as a building block for the synthesis of the spirotetronic acid structure of chlorothricolide

摘要: The Diels-Alder reaction of the title compound 4 and octatrienol 10, which were prepared from 4-methoxy-5-methylene-2(5H)-furanone furfuryl alcohol or D-glyceraldehyde, respectively, produced in high yield a mixture stereo- regio-isomeric spirotetronates: 14, 15, 16 about 65:25:10 ratio. exo-mode adduct 15 (R= 2,4-difluorophenyl) was transformed into carboxylic acid 19, tetronic subunit chlorothricolide (1), also to 21 can be utilized synthesis 1.