trans-cycloalkenes. Part 9. Optically active trans-cyclo-octenes via resolution of β-hydroxyphosphine oxides. Proof of configuration of bicyclic trans-cyclo-octenes constrained in chair and twist conformations

Abstract

β-Hydroxyphosphine oxide precursors to trans-cyclo-octenes have been resolved by crystallisation of their menthoxyacetates. Subsequent fragmentation using sodium hydride gives the respective optically active trans-cyclo-octenes. In this way (S)-(+)- and (R)-(–)-trans-cyclo-octene, (S)-(+)-cis,trans-cyclo-octa-1,5-diene, and 4,5-epoxy-trans-octene [(+)-(12)] have been obtained in high optical purity. The epoxy-olefin (+)-(12) can be converted via addition of butadiene, and epoxide opening with lithium diphenylphosphide, into the optically active hydroxyphosphine oxides (+)-(14) and (+)-(15) which are respectively precursors of the optically active bicyclic twist and chair trans-cyclo-octenes (+)-(3) and (–)-(4). Addition of butadiene to (+)-(3) gave (+)-(17) while addition to(–)-(4) gave the meso-compound (18). In this way the twist and chair olefins were identified. Absolute configurations to all the optically active compounds have been assigned by correlation with (S)-(+)trans-cyclo-octene.