Allylic trialkylstannanes

The Lewis acid-promoted addition of allylic trialkylstannanes to achiral aldehydes has been demonstrated to provide syn homoallylic alcohols in high yield [71 a,b]. The relative stereochemical outcome of the reaction of simple aldehydes with 2-butenylstannanes is discussed earlier in this Chapter. Studies on the addition of al- 

The Lewis acid-promoted addition of allyltributylstannane and ( )-85 to /i-alk-oxy aldehydes has also been investigated [84c]. The Lewis acid-promoted reaction of a 9-siloxy aldehyde 106 with ( )-85 affords almost entirely the syn homo- 

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In the elaboration of /Mactam derivatives, an allyl group has been introduced alpha to the carbonyl group by reaction of an a-bromo-/Mactam with an allyl trialkylstannane under radical conditions (equation 113)704. The allyl group is introduced in a stereospecific fashion, thus indicating how useful radical reactions can be in the synthesis of complex molecules ... 

The effects of the cr—JT interaction on the ground-state properties of allyltrimethylmetal compounds are paralleled by the effect on reactivity towards electrophilic reagents. Mayr demonstrated that allyltrialkylsilanes, allyltrialkyl-germanes, and trialkylstannanes react with diphenylcarbenium ions at rates 105,5.6 x 105, and 109, respectively, relative to propene.158 The reaction rates were also found to be sensitive to the inductive effects of the other substituents attached to the metal. A theoretical evaluation of the factors determining the regiochemistry and stereochemistry of electrophilic addition to allylsilanes and other allyl systems is reported by Hehre et al.159 They predict a preference for electrophilic attack anti with respect to the silane substituent, a prediction that is supported by many experimental studies.82,160... 

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