Grignard reagents vinyl substitution

Nucleophilic additions of ethyl-, vinyl-, and ethynyl-lithium and Grignard reagents to a 2-alkyl-substituted cycloheptanone have been found to yield the corresponding cw-cycloheptanol preferentially. The selectivity, which increases with size of the nucleophile, has been attributed to a combination of steric repulsions and torsional effects in the transition state. Application of the MM2 force field to analyse nucleophilic attack of hydride and ethynyl lithium on 2-methylcycloheptanone gave results comparable to those obtained experimentally and from ab initio calculations. 

Substituted indoles from the reaction of ort/jo-substituted nitroarenes and vinyl Grignard reagents. 

Direct substitution reaction of 125 <1995EJM697> with organozinc reagents derived from allyl, benzyl, phenyl, vinyl, and -butyl Grignard reagents stereoselectively produced C-lO-substituted deoxoartemisinins 142 in good to moderate yields (Scheme 17 Table 12) <2002TL2891>. 

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