The total syntheses of cybrodol (1), isocybrodol (2), cybrodal (3), cybrodic acid (4), and trisnorcybrodolide (5), starting from 2-bromomesitylene (6) are described. The route involves oxidation of the 5-methyl group of 6 by means of chromyl acetate, addition of the β-hydroxyethyl chain by aryllithiation and reaction with ethylene oxide, and addition of the fifth carbon substituent by aryllithiation and treatment with ethyl chloroformate to give the key intermediate, methyl 3-(2-hydroxyethyl)-6-methoxymethyl-2,4-dimethylbenzoate (18d). The latter was transformed into trisnorcybrodolide (5), and further elaborated via the corresponding aldehyde 21 into the remaining cybrodins.
本文描述了从2-溴二甲苯(6)出发,合成环孢多醇(1)、异环孢多醇(2)、环孢醇(3)、环孢酸(4)和三降环孢内酯(5)的总过程。该路线涉及通过铬酰醋酸氧化6的5-甲基团,通过芳基锂化和与环氧乙烷反应添加β-羟乙基链,并通过芳基锂化和用氯甲酸乙酯处理添加第五个碳取代基,得到关键中间体,即甲基3-(2-羟乙基)-6-甲氧甲基-2,4-二甲基苯甲酸酯(18d)。后者被转化为三降环孢内酯(5),并通过相应的醛21进一步细化成剩余的环孢素。