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The substitution of alkoxy groups of enol ethers (1-methoxycyclohexenes, 1-methoxy-l-alkenes, and benzofuran) and aryl ethers (methoxynaphthalenes, cresyl methyl ethers, and dimethoxybenzenes) by hydrogen, alkyl groups, and aryl units, through Grignard reactions catalyzed by bis(triphenylphosphine)nickel dichloride or [1,3-bis-(diphenylphosphino)propane]nickel dichloride, is described. The stereochemistry of the new reaction is portrayed, especially in connection with processes involving ring opening of dihydropyrans and dihydrofurans. The reaction has been applied to the synthesis of a termite trail pheromone and the acetate of the Douglas fir beetle aggregation pheromone.

The -C NMR spectra of lupeol and related triterpenes were recorded and all carbon shifts assigned. Their analysis aided in the shift assignment of the strncturally related hopane-like triterpenes.After early work on some tetracarbocyclic triterpenes2s3 there appeared 13C NMR analyses of a-and pamyrinic pentacarbocyclic substance^.^,^ However, except for a report on two hopanes from an oil shale deposit' and the use of a limited number of friedelin shifts for the interpretation of @effects in transdecalin systems6 little is known about the 13C NMR spectroscopy of non-amyrin types of pentacarbocyclic triterpenes. The present communication concerns a 13C NMR study of a large number of lupeol-derived substances and some hopane derivatives. Their shift assignments utilized off-resonance decoupling techniques for the determination of the substitution profile of carbon centers, functionality manipulation causing predictable shift variations, shift assessment utilizing 13C NMR data for carbocyclic systems of known stereochemistry and conformation, especially those of decalins,7.8 perhydr~phenanthrenes,~ diterpenes [e.g. ll0-l3 (the shift assignment of hinokiol (1) is based on that of ferruginol" and of ring A of lano~terol)~] and steroids 14and lanthanide-induced shift measurements.

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Aryltrimethylammonium iodides are shown to undergo reaction with Grignard reagents under phosphine-ligated, low-valent nickel catalysis with the formation of alkylarenes and biaryls. Some time ago there was introduced a new method of carbon-carbon bond formation based on the replacement of the alkoxy group of vinyl or aryl ethers by an alkyl or aryl substituent on exposure of the ethers to Grignard reagents under phosphine-ligated, low-valent nickel catalysis.' This discovery was followed by a second procedure involving the replacement of the alkylthio unit of vinyl or aryl thioethers by alkyl or aryl functions under similar circumstances.2 The

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