3-Methyl-l -phenyl-2-butene

The neomenthylcyclopentadienyl analog (S-2) of (1) undergoes the same reaction to give (+)-(R,R)-2-methyl-l-phenyl-3-butene-l-ol (3) in >98% ee (equation II). 

A soln. of 1,3-butadiene in THF added at 0 to a soln. of (PhMe2Si)3MnMgMe (prepn. s. Synth. Meth. 41, 583) in ether/THF, stirred for 15 min, benzaldehyde added, stirring continued for 1 h at room temp., dil. with hexane, and quenched with satd. aq. NH4CI (E)-4-(dimethylphenylsilyl)-2-methyl-l-phenyl-3-buten-l-ol. Y 70%. F.e. and electrophiles s. K. Fugami et al.. Tetrahedron 44, 4277-92 (1988). 

Chiral compounds of this class condense with aldehydes to give a reasonable degree of enantioselective synthesis of homoallylic alcohols. Reaction of (-)-(S)-(neomenthylcyclopentadienyl) Mo(NO)Cl(Ji-syn-crotyl) 47 with benzaldehyde affords (+)-( , /f)-2-methyl-l-phenyl-3-buten-l-ol 48 with >98% ee. (+) and (-) chiral... 

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