反应详情

The Heather synthesis of 2-(6-carboxy-2-cis-hexynyl)-cyclopentane-1,3,4-trione implicitly includes a process for preparing 9-oxo-5-decynoic acid (I; n=3, R=H). Table A provides a synopsis of that synthesis which consists of: first treating 2-methyl-2-(3-butynyl)-1,3-dioxolane, III, with lithium amide in liquid ammonia and then with 1-bromo-4-tetrahydropyranyloxybutane, IV, in tetrahydrofuran to obtain 2-methyl-2-(8-pyranyloxy-3-oxtynyl)-1,3-dioxolane, V; hydrozyling V to 9-oxo-5-decyn-1-ol, VI; oxidizing VI with Jones's reagent (CrO3, H2SO4) to 9-oxo-5-decynoic acid; esterifying the latter with methanol under acidic catalyss to obtain methyl-9-oxo-5-decynoate, VII; hydrogenating VII over Pd/BaSO4 (Lindlar's catalyst) in quinoline to get methyl 9-oxo-5-cis-decenoate, VIII; condensing VIII with diethyl oxalate in the presence of sodium ethoxide in ethanol to obtain 2-(6-carbomethoxy-2-cis-hexenyl)-5-(ethoxyalkyl)-cyclopentane-1,3,4-trione, IX; and hydrolyzing IX under acidic conditions to obtain 2-(6-carboxy-2-cis-hexenyl)-cyclopentane-1,3,4-trione (II: n=3: R= H).