Efficient enantioselective hetero-Diels-Alder reaction of Brassard's diene with aliphatic aldehydes: a one-step synthesis of (R)-(+)-kavain and (S)-(+)-dihydrokavain.
An efficient catalytic asymmetric hetero-Diels-Alder reaction of Brassard's diene with aliphatic aldehydes was reported. The catalyst, which was generated from (R)-BINOL, Ti(i-PrO)4, and 4-picolyl chloride hydrochloride, promoted the reaction smoothly to afford the corresponding alpha,beta-unsaturated delta-lactone derivatives in moderate-to-good yields (46-79%) with high enantioselectivities (up to 88% ee). Natural products (R)-(+)-kavain (70% ee, >99% ee after single recrystallization) and (S)-(+)-dihydrokavain (84% ee) were also prepared in one step by using this methodology.
Lin
Lili
L
Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, China.
Chen
Zhenling
Z
Yang
Xu
X
Liu
Xiaohua
X
Feng
Xiaoming
X
D000447:Aldehydes / Q000737:chemistry*; D011753:Pyrones / Q000138:chemical synthesis*; D013237:Stereoisomerism
D000447:Aldehydes; D011753:Pyrones; C113859:dihydrokavain; C011889:kavain