(2S)-1-(4-nitrophenyl)sulfonylpyrrolidine-2-carboxylic acid → trans-3-bromo-6-cyano-3,4-dihydro-2,2-dimethyl-4-(N-4-nitrobenzenesulfonyl-L-prolyloxy)-2H-1-benzopyran

Beteiligte Stoffe

Reaktionsschritte

A similar procedure as in Example 1(1) was performed by using 6.7 g of N-4-nitrobenzenesulfonyl-L-proline and 5.7 g of (±)-trans-3-bromo-6-cyano-3,4-dihydro-2,2-dimethyl-2H-1-benzopyran-4-ol to give 4.72 g of trans-3-bromo-6-cyano-3,4-dihydro-2,2-dimethyl-4-(N-4-nitrobenzenesulfonyl-L-prolyloxy)-2H-1-benzopyran as a sparingly soluble diastereomer compound, melting at 226.5°-227° C. with decomposition, [α]23D =+44.7° (c=1, CHCl3) and 5.01 g of the corresponding readily soluble diastereomer compound, melting at 177°-180° C., [α]23D =-93.2° (c=1, CHCl3), respectively.

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