1,3-Dioxanone Derivatives from ?-Hydroxy-carboxylic Acids and Pivalaldehyde. Versatile Building Blocks for Syntheses of Enantiomerically Pure Compounds. A Chiral Acetoacetic Acid Derivative Preliminary Communication
作者:Dieter Seebach、J�rg Zimmermann
DOI:10.1002/hlca.19860690523
日期:1986.7.30
(R)-3-Hydroxybutyric acid (from the biopolymer PHB) and pivalaldehyde give the crystalline cis - or (R,R)-2-(tert-butyl)-6-methyl-1,3-dioxan-4-one (1a), the enolate of which is stable at low temperature in THF solution and can be alkylated diastereoselectively (3, 4, 5, and 7). Phenylselenation and subsequent elimination give an enantiomerically pure enol acetal 10 of aceto-acetic acid. Some reactions of
(R)-3-羟基丁酸(来自生物聚合物PHB)和新戊醛生成顺式或(R,R)-2-(叔丁基)-6-甲基-1,3-二恶烷-4-酮(1a),其烯醇化物在THF溶液中在低温下稳定,并且可以非对映选择性地烷基化(3、4、5和7)。苯硒化和随后的消除得到对映体纯的乙酰乙酸烯醇缩醛10。已经进行了10次反应,例如迈克尔加成反应(11),CH 3取代基上的烷基化反应(13),CC键的氢化(1a)和光化学环加成(16)。整个反应是在起始β-羟基酸的一个立体异构中心取代而不发生消旋作用且不使用手性助剂。