With -N-methylephedrin

A chiral hydride complex, tentatively assumed to be 86, prepared by partially reacting LAH with (- )-N-methylephedrine (1 equivalent) and /V-ethylaniline (2 equivalents) was found to reduce 2-acetyl-5,8-dimethoxy-3,4-dihydronaphtha-lene (87) quantitatively to the (- )-carbinol (88) with 92% e.e. (94,95). Carbinol 88, which was obtained optically pure by recrystallization, could be converted to (/ )-(-)-2-acetyl-5,8-dimethoxy-l,2,3,4-tetrahydro-2-naphthol (89). The lat-... 

Synthesis of the acyclic portion began, as in the previous synthesis, with enantiomerically pure citronellol (25). Protection of the alcohol as the benzyl ether and oxidative cleavage of the olefin to the aldehyde gave 26 (85%). Chain extension via the masked acyl anion equivalent 27, alcohol protection, and concomitant -elimination and isomerization of the allene to die alkyne with butyl lithium gave 28. The resulting protected ketone must now be converted to the P-alcohol required for the completion of the synthesis. Thus hydrolysis to die ketone followed by enantioselective reduction with (—)-N-methylephedrine-... 

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