Synthesis of y-Lactams from Conjugated Diene-Magnesium Reagents

10 Synthesis of y-Lactams from Conjugated Diene-Magnesium Reagents 

Most approaches to y-lactams have relied on cyclization via acyl-nitrogen bond formation [130]. Cyclization involving carbon-carbon bond formation is an alternative route however, until recently this approach has received little attention. Mori and coworkers reported a palladium-catalyzed cyclization of A -allyl iodoacetamides, in which the intramolecular addition reaction of the carbon-iodine bond to an olefinic linkage is a key step [131]. 

Itoh and coworkers developed a new route to y-lactams by the ruthenium-catalyzed cyclization of A -allyltrichloroacetamides [132]. Also, Stork and Mah have reported on the radical cyclization ofAT-protected haloacetamides to yield AT-protected lactams. The protecting groups can then be easily removed under a variety of conditions [133]. This efficient radical cyclization route to c -fused pyrrolidones and piperidones is interesting because of the widespread occurrence of related systems in natural products [134]. We have developed a direct method for the one-pot synthesis of y-lactams and secondary amines utilizing conjugated diene-magnesium complexes [135]. 

2- bis(methylene)cyclohexane and provided a facile route to a spiro-y-lactam, p-((2-methylene)cyclohexyl)-y-phenyl-Ar-benzyllactam, in 36% isolated yield. 

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Table 7 Synthesis of y-Lactams from Conjugated Diene-Magnesium Reagents, Imines, and CO2...

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