Bromoacetate Olefination Protocol for Norbixin and Julia–Kocienski Olefination for Its Ester Syntheses

[Image: see text] A new olefination protocol utilizing ethyl bromoacetate was highlighted, in which magnesium enolate of the ester coupled with C(20) dialdehyde 6, and double eliminations of the protected hydroxyl groups and bromine atoms of the coupling bromohydrin product, efficiently produced norbixin 1 after concomitant hydrolysis of the ester. A new (C(7) + C(10) + C(7)) disconnection approach was demonstrated for the synthesis of norbixin ethyl ester 2 by the Julia–Kocienski olefination of novel C(7) benzothiazolyl-sulfone 11 and C(10) 2,7-dimethyl-2,4,6-octatrienedial (12).