Conjugate addition to chiral γ-heterosubstituted δ-lactones as pivotal synthons from L-glutamic acid. Synthesis of an optically active lignan lactone; (−)-hinokinin
Asymmetric induction in conjugateaddition of new chiral γheterosubstituted-α,β-unsaturated α-lactones from L-glutamic acid was accomplished in high diastereoselectivity with the formation of trans(R,S)-adducts and was disclosed to serve as a versatile procedure for the asymmetric synthesis of antileukemic lignanlactones.
β-amino acid N-Boc-ADDA is prepared following a disconnection of the CC bond between the two E,E double bonds. The stereochemistry of the two synthons was controlled using the alkylation of chiral bromoallenes derived from naturally occurring (S)-serine and (S)-phenyllactic acid. The cupration of bromoallenes derived from (S)-serine also provides a general method for the synthesis of chiral β-alkylated