Silastannation allenes

Highly regio- and stereoselective silastannation is achieved by employing phosphine-free Pd(dba)2 as the catalyst (Equation (119)).2 The addition takes place at the less substituted allenic C=C bond to afford /3-silyl (E)-... 

The palladium-catalyzed silastannation of bis(allene)s gives trans-cyclized product stereoselectively (Equation (121)).162 This stereochemical outcome stands in contrast to the distannation of the bis(allene)s, which affords m-cyclized product. 

Kang et al. demonstrated that the palladium-catalyzed tandem cyclization—silastannation of the bis(allene) 72 with trimethylsilyltributyltin 70 produced the trans fused heterocycle 73 (Scheme 25),... 

Regio- and stereoselectivities in Pd-catalyzed silylstaimation (silastannation) of allenes are not always satisfactory. They are markedly improved by the use of phosphine-free Pd catalyst, particularly Pd2(dba)3. The allylstannane 141 was... 

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See also in sourсe #XX -- [ ]

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