The novel, enantiomerically enriched nine-and ten-membered cyclic allenes (+)-5a−c and (−)-6a−c were synthesized by lipase-catalyzed kinetic resolution of propargylic acetates 1/2 and subsequent anti-stereoselective S N 2Ј-substitution with magnesium cuprates. The CD spectra of these allenes

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The synthesis and the crystal structure analysis via X‐ray diffraction of the title compound, C20H28O4, (I), are described. The title compound is a camphanic acid cyclo­decynyl ester. This compound contains a ten‐membered ring including a triple bond and is prepared by condensation of (1S)‐(−)‐camphanic acid chloride with (R)‐(+)‐cyclo­dec‐2‐yn‐1‐ol [(II), 90% ee]. This alcohol [Hanack & Wächter (1987). Chem. Ber. 120, 727–734] has been isolated by kinetic deracemization of the corresponding acetate [Zelder (2001). PhD Thesis. In preparation] with the lipase from mucor miehei. With this structure analysis, the configuration of (II) was determined.

Introduction Dienes Enynes Polyenes