Homocinnamyl alcohol

Oshima and coworkers have developed a new epoxide ring-opening methodology treatment of a mixture of epoxide and styrene with trimethylsilylmethylmagnesium bromide in the presence of a cobalt-phosphine complex afforded the corresponding homocinnamyl alcohols in good yield (Scheme 35) <2004ASC1631>. 

A more efficient and more generahy applicable cobalt-catalysed Mizoroki-Heck-type reaction with aliphatic halides was elegantly developed by Oshima and coworkers. A catalytic system comprising C0CI2 (62), l,6-bis(diphenylphosphino)hexane (dpph 73)) and Mc3 SiCH2MgCl (74) allowed for intermolecular subshtution reactions of alkenes with primary, secondary and tertiary alkyl hahdes (Scheme 10.25) [51, 53]. The protocol was subsequently applied to a cobalt-catalysed synthesis of homocinnamyl alcohols starting from epoxides and styrene (2) [54]. 

The reaction of epoxides with styrene provides homocin-namyl alcohols in good yield (eq 34). The reaction involves ring-opening of the epoxide to yield the magnesium alkoxide of a vtc-halohydrin, which then undergoes the cobalt-catalyzed styrylation. Use of trimethylsilylmethylmagnesium bromide and cobalt(II) bromide, instead of chlorides, facilitates the reaction of epoxide since the more nucleophilic bromide efficiently attacks the epoxide. Conversion of tosylaziridines affords homocinnamyl amines. 

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