Marshall synthesis

In a variation of these reactions, Grieco and Masaki used p-toluenesulfonyl groups to direct alkylation reactions in the formation of carbon chains and then cleaved the sulphones with lithium in ethylamine. This type of synthetic construction involving the use of sulphur-containing molecules has become a typical sequence in organic syntheses. In this case, the reactions formed part of successful syntheses of squalene and sesquifenchene and were carried out without any migration or loss of stereochemical integrity of the double bonds. Similar sequences have been reported by Trost (prenylation reactions) and Marshall (synthesis of a cembranoid precursor). 

The Marshall synthesis clearly demonstrated both the versatility of allenyl metal methodology for the preparation of polypropionate arrays and the utility of the Suzuki cross-coupling in complex fragment assembly. 

Hydroazulenes. Startg. l,2-epoxy-2-methyl-3-methylenebicyclo[4.4.0]decane distilled slowly at 380-385°/4.5 mm under Ng through a column of sand cis-l-methyl-10-methylenebicyclo[5.3.0]decan-2-one. Y 75%. R. A. Kretdimer and W. J. Frazee, J. Org. Chem. 36, 2855 (1971) synthesis of hydroazulenes, review, s. J. A. Marshall, Synthesis 1972, 517. 

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