Amines Cram product

As already shown in Section B.I, certain organotitanium reagents readily form isolable, octahedral 1 2 adducts with such donor molecules as THF, glyme, thio-ethers, amines and diamines1,19) (Equation 47). In case of methyltitanium trichloride 17, structural data show the methyl group to occupy the equatorial position 96). In order to test whether such molecules undergo stereoselective addition to aldehydes (Equation 47), we reacted 134, 135 and 136 (prepared from TMEDA, glyme and THF, respectively) with 2-phenylpropanal 12491. The 125 126 ratios of 80 20, 82 18 und 85 15 show that the Cram product is preferred in all cases... 

Asymmetric reactions have also been developed. The reactions of allyltitaniums with chiral aldimines derived from optically active 1-phenylethylamine afford optically active homoallylic amines with excellent diastereofacial selectivities. Thus, the Cram syn addition products are obtained highly predominantly when using crotyltitanium reagent 33, as exemplified in Scheme 13.30 [61]. 

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