Hydroborated bisalkenes

An equivalent reaction has been achieved via the treatment of hydroborated bisalkenes with alkaline silver nitrate solution (Table 1.4).22,23 This method has been used to synthesize a number of small and medium-size carbocyclic rings in moderate to good yield. The selectivity for terminal cyclization observed for 1,6-heptadiene and 1,7-octadiene indicates that, in these cases, hydroboration of each of the alkenes occurs independently to yield acyclic boranes. It has, however, been found that both cyclic and acyclic boranes react under these conditions to yield the ring-closed products (Scheme 1.3). 

TABLE 1.4. Silver-Mediated Ring Closing of Hydroborated Bisalkenes... 

Hydroboration-carbon monoxide insertion of bisalkenic amino derivatives (210) provided facile preparations of 5-azacyclooctanes (211). Reductive ring closure afforded pyrrolizidines (212) <82JOC1494>. 

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See also in sourсe #XX -- [ ]

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