Absolute configuration of trisporic acids and the stereochemistry of cyclization in β-carotene biosynthesis

Abstract

The absolute stereochemistry of trisporic acid C (1) is 1S, 13R; the 1α-methyl, which is equatorial, is selectively labelled by [2-¹⁴C]mevalonate, and corresponding chirality at C-1 in [2-¹⁴C]mevalonate-labelled β-carotene is thereby indicated with implications for the stereochemistry of cyclization in β-carotene biosynthesis.