Electrophilic Attack on Coordinated Double Bond Systems

Electrophilic Attack on Coordinated Double Bond Systems 

C-C bond formation resulting from electrophilic attack on coordinated double-bond systems is a useful synthetic reaction (Section lll,B). The formation of C-X bonds by electrophilic attack of X, however, is restricted essentially to or D. Electrophiles such as Br or NOj usually lead to oxidative cleavage of the metal-olefin complex, although NBS (iV-bromosuccinimide) has been reported to act as a hydride acceptor in some cases (Khand et al., 1968, 1969). 

C-H or C-D bond formation is usually a stereospecific process in which the electrophile attacks the double-bond system on the same side as the metal atom [Eqs. (126), (127) (Whitesides and Arhart, 1971), (128) (Winstein et al., 1965), (129), (130) (Birch and Williamson, 1973 A. J. Birch, B. J. Chauncy, and D. J. Thompson, unpublished results, 1975 and (131) (Birch et al., 1973b A. J. Birch, B. J. Chauncy, and D. J. Thompson, unpublished results, 1975)]. 

One example of a stereospecific deuteration on the side of the molecule opposite the tricarbonyliron group has been observed [Eq. (132) (Hunt et al.. 

The l-C02Me complex above undergoes base-catalyzed exchange with MeO . MeOD to introduce a 5a-D (A. J. Birch, B. J. Chauncy, and D. J. Thompson, unpublished results, 1975). This would be expected on the basis of an anionic intermediate. 

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B. Electrophilic Attack on Coordinated Double Bond Systems... 

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