(S),(E)-5-Methoxycarbonyl-3-triphenylmethylaminohex-4-en-4-olide

The title compound, C₂₇H₂₅NO₄, is the minor product of the Wittig reaction of (S)-N-triphenylmethylaspartic anhydride with the stabilized ylide Ph₃P=C(Me)CO₂Me. The crystal structure determination unambiguously shows that this product is not the originally proposed Z isomer of the major product (S),(E)-5-methoxycarbonyl-2-triphenylmethylaminohex-4-en-4-olide, but the alternative α-adduct, also with an E configuration at the C4=C5 double bond.

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