Lateral lithiation diastereoselectivity

Lateral lithiation of (d )-4-isopropyl-2-(o-tolyl)oxazoline and reaction with aldehydes provides the addition products 1148 with moderate to good diastereoselectivity. The addition of TMEDA is vital for any diastereoselectivity to be observed. The major (,S,A)-products lactonize faster under acidic conditions providing dihydroisocoumarins 1149 in up to ee 97% (Scheme 286, Table 53) <2005T3289>. Similarly, the addition of laterally metallated o-toluates to chiral aldehydes provides a key dihydroisocoumarin during a total synthesis of AI-77-B <1999J(P1)1083>. 

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