Tris methyl alcohol, intramolecular

The 8-methyl-8,14-cycloberbine 364, derived from the protoberberine 324 via the betaine 363, was reduced with sodium borohydride or lithium aluminum tri-tert-butoxyhydride to give a diastereoisomeric mixture of cis-and trans-alcohols (7.8 1 or 1 7.8, respectively) (Scheme 64).t)n exposure to formaldehyde the mixture underwent N-hydroxymethylation and subsequent intramolecular substitution on the aziridine ring to give the oxazolidine 365. Removal of the hydroxyl group in 365 was accomplished by chlorination followed by hydrogenolysis with tributyltin hydride. Reductive opening of the oxazolidine 366 with sodium cyanoborohydride afforded ( )-raddeanamine (360), which has already been converted to ochotensimine (282) by dehydration. 

MonolerpeneB. M. may be considered formally as dimerization products of isoprene (2-methyl-1,3-butadiene, CsHg) and have a C,o skeleton. For biogenesis, see teipenes. The class of M. includes not only acyclic but also mono- and bicyclic hydrocarbons and their oxidation products (alcohols, aldehydes, ketones, and acids). Tri- and tetracyclic M. are very rare. The simplest acyclic M. are geraniol and nerol (see geraniol), from which mono- and bicyclic M. are formed by intramolecular cyclization. The most important caition skeletons of the monocyclic M. are illustrated in formulae 1-6. 

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