Regiocontrolled, Palladium-Catalyzed Bisfunctionalization of Allenyl Esters. Multicomponent Coupling Approaches to Highly Substituted α,β-Unsaturated δ-Lactones
作者:Chad D. Hopkins、Lisa Guan、Helena C. Malinakova
DOI:10.1021/jo050886v
日期:2005.8.1
6-Ph-disubstituted α,β-unsaturated δ-lactones in 62−78% yields. Lactones derived from aromatic, heteroaromatic, and vinylic aldehydes were isolated in 51−58% yields, while aliphatic aldehydes were less reactive. The regiochemistry of bisfunctionalization of allenyl ester homologues remained controlled by the ester substituent, and the reactions afforded cis-4,5,6-trisubstituted α,β-unsaturated δ-lactones and
证明了钯催化的烯基酯与硼酸(亲核试剂)和醛(亲电子试剂)的区域选择性双官能化。三组分偶联在温和条件下提供了出色的化学选择性,区域选择性和非对映选择性的α,β-不饱和δ-内酯。芳族,杂芳族和乙烯基硼酸(R 1 B(OH)2)与2,3-丁二烯酸乙酯和苯甲醛反应生成相应的4-R 1,6-Ph-二取代的α,β-不饱和δ-内酯的产率为62-78%。分离出芳香族,杂芳香族和乙烯基醛类的内酯,收率为51-58%,而脂肪族醛的反应性较低。丙二烯基酯的同系物的bisfunctionalization的区域化学仍然由酯取代基控制,并且反应,得到顺式-4,5,6-三取代的α,β不饱和δ内酯和(的酯Ž) -顺式-3,4,5-三取代-5-羟基-2-戊烯酸的总收率为47-65%。在各种钯(II)催化剂中,证明了具有衍生自β-pine烯的辅助烯丙基配体的π-烯丙基铝(II)二聚体催化剂的优异性能。提出了一种以不对称双-