A Stereospecific Total Synthesis of α-Santalol

A stereospecific synthetic route to the important constituent of sandalwood oil, α-santalol, from the readily accessible (–)-π-bromotricyclene is outlined. The synthesis illustrates a number of new synthetic methods including (1) chain extension using 3-trimethylsilylpropargyllithium, (2) stereo- and position-specific addition of diisobutylaluminum hydride to the lithium salt of a propargylic alcohol, and (3) stereospecific methoxycarbonylation of a vinylic iodide by nickel carbonyl and sodium methoxide in methanol. The scope of the synthesis as a general route to the structural olefinic unit RCH₂CH=C(CH3)CH₂OH in which H and CH3 are cis is further illustrated by the case R = n-C6H13.