52486-23-4

Four optically active 4-cyanocaranes diastereoisomers have been synthesized starting from (+)-car-3-ene and their structures supported by chemical evidences and X-ray analysis.

Commercially available (+)-3-carene (4) is shown to be capable of efficient conversion to vinyl bromides 28, 46, and 49 and to vinyl stannane 44.All four compounds stem from (+)-3-norcaranone (23), an optically pure ketone best prepared by epoxidation of 4, followed by oxirane ring opening, acetylation, ozonolysis, and CrCl2-promoted reduction.The strong proclivity exhibited by 23 to enolize in the cyclopropyl carbinyl sense is used to advantage to gain entry to 28 and 44.Remarkably, the tosylhydrazone of (+)-3-norcaranone (45) is distinguished from its ketoneprogenitor 23 by its capacity for highly regioselective deprotonation from the alternative α-position.The crossover has made possible synthetic access to 46 and 49.Other chemistry of this class of compounds is also presented, inluding a route to 51, a vinyl bromide epimeric to 49.Especially relevant to future work in the ingenol area is the ability of these molecules to serve as nucleophiles.Several reactions involving 28 are provided as exemplary of this property.

A first example of electrochemical hydroboration of olefins was found.Anodic oxidation of sodium borohydride in the presence of olefins in diglyme followed by conventional oxidation gave the corresponding alcohols regio- and stereoselectively in good yields.

Reactions of hydroxyl radicals, generated by photodecomposition of hydrogen peroxide in acetonitrile, with a wide variety of cycloalkenes have been examined.The results show that the major reaction is the addition of hydroxyl radicals to the less substituted end of the double bond, furnishing the secondary alcohols.The reactivity pattern and the observed regio- and stereoselectivity clearly reveal that the steric parameters associated with the substrates play a dominant role in directing the addition reactions.More importantly, this study led to the development of a new methodology for the facile conversions of olefins essentially into secondary alcohols, and includes a few examples which demonstrate the potential of the method.