Asymmetric hetero Diels-Alder reaction catalyzed by stable and easily prepared CAB catalysts

Tetrahedron Vol. 50, No. 15. p. 4555, 1994 Elseviu Science Ltd F’rintedin Great Britain 0040-4020194 S6.OCM.00

Asymmetric

Hetero Diels-Alder Reaction Catalyzed by Stable and Easily Prepared CAB Catalystsf

Qingzhi Gao, Kazuaki Lshihara, Tohru Maruyama, School of Engineering,

Manuscript

Makoto Mouri and Hisashi Yamamoto*

Nagoya University, Chikusa, Nagoya 464-01, Japan

published

in Tetrahedron 1994.50,

979-988.

Abstract:

A stable chiral (acyloxy)borane (CAB) complex is prepared in situ by mixing a tartaric acid A solution of the catalyst is effective in derivative and different arylboronic acids at room temperature. catalyzing hetero Diels-Alder reactions of electron rich dienes with conjugated aldehydes to produce dihydropyrone derivatives of high optical purities.

i-Pro

0 On

OMe

tt3

Oi-Pr

&O

1 R

(20 mol%), EtCN, -78 “C

R

G ‘0

0

R

R

R’= H. Me

%edicated with respect to Professors Prize for 1993.

Ryoji Noyori and K. Barry Sharpless on the occasion of the Tetrahedron

4555