Scientific article
English

Asymmetric Diels-Alder Reactions of Neopentyl-Ether-Shielded Acrylates and Allenic Esters: Syntheses of (-)-Norbornenone and (-)-β-Santalene

Published inHelvetica chimica acta, vol. 68, no. 8, p. 2100-2114
Publication date1985-12-18
Abstract

Starting from (+)- or (−)-camphor, the antipodal alcohols 14 and 18, respectively, have been prepared; the corresponding acrylates 15 and 19 underwent TiCl2(i-PrO)2-mediated Diels-Alder additions to cyclopentadiene to give adducts 20a and 22a respectively, with 95 % endo- and 99.2% πpH-face selectivities. Adduct 22a was converted to enantiomerically pure norbornenone 26. Addition of 1,3-butadiene to acrylate 15 in the presence of TiCl4 afforded 3-cyclohexenyl carboxylate 29 with > 95.6 % stereodifferentiation. The TiCl2(i-PrO)2-promoted [4 + 2] cycloaddition of cyclopentadiene to allenic ester 43 proceeding with 99 % face differentiation served as the key step for an efficient enantioselective synthesis of (−)-β-santalene ((−)-41) with concomitant recovery of the chiral control alcohol 14.

Citation (ISO format)
VON OPPOLZER, Wolfgang et al. Asymmetric Diels-Alder Reactions of Neopentyl-Ether-Shielded Acrylates and Allenic Esters: Syntheses of (-)-Norbornenone and (-)-β-Santalene. In: Helvetica chimica acta, 1985, vol. 68, n° 8, p. 2100–2114. doi: 10.1002/hlca.19850680803
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Journal ISSN0018-019X
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