Reactions of Nucleophilic 7r-Allyl Complexes

Allyl complexes of some other transition metals, such as Ru, Fe, Cr and Ti, are also used for synthetic purposes. Reaction of allylic acetates with aldehydes catalyzed by a Ru complex in the presence of Et3N and CO gives the alcohol 39. It seems likely that the reaction itself is stoichiometric. But a high-valent Ru complex, formed by the reaction with the electrophile, is reduced to a lower valences with Et3N or CO, making whole reaction catalytic [2,13], 

Vinyloxiranes are used for facile 7i-allyl complex formation [14], The -allylic ferralactone complex 41 was prepared by oxidative addition of Fe2(CO)9 to the functionalized vinyloxirane 40 and CO insertion. Treatment of the ferralactone complex 41 with optically active a-methylbenzylamine (42) in the presence of ZnCl2 gave the 7r-allylic ferralactam complex 45 via 44. In this case, as shown by 43, the amine attacks the terminal carbon of the allylic system and then the lactone carbonyl. Then, elimination of OH group generates the 7r-allylic ferralactam complex 45. Finally the /1-lactam 46 was obtained in 64% yield by oxidative decomplexation with Ce(TV) salt. The 5-lactam 47 was a minor product (24%). The precursor of the thienamycin 48 was prepared from 46 [15,16]. This mechanistic explanation is supported by the formation of both 7r-allyllactone and lactam complexes (49 and 51) from the allylic amino alcohol 50 [17]. 

The nucleophilic 7i-allyltitanium complex 67 is prepared by the reaction of the conjugated diene 65 with titanocene hydride 66, generated in situ by the treatment of titanocene dichloride with 2 moles of z-PrMgCl [21]. The complex is nucleophilic and reacts with aldehydes regio- and stereoselectively to give homoallylic alcohols [22]. 

The / ,y-unsaturated ester 68 was prepared by the reaction of the 7r-allyltitanium complex 67 with methyl chloroformate [23], 

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