l-Prolinol as a chiral auxiliary in the photochemical synthesis of a new aryltetraline lignan analogue

Prochiral (E,E)-fulgide 8 was reacted with l-prolinol to afford cyclic (M)-fulgamide 10 in a two step reaction sequence. The UV-light-driven photocyclization of 10 proceeded stereospecifically, giving lignan analogue 1 in 40% yield. The structure of 1 was confirmed by X-ray crystallography.

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(M)-(E,E)-2,3-Bis-(4-methoxy-α-phenylethylidene)succinate l-prolinol cyclic amide esterC27H29NO5[α]D20=+42 (c 0.30, CHCl3)Source of chirality: l-prolinolAbsolute configuration: (M, S)

(P)-(E,E)-2,3-Bis-(4-methoxy-α-phenylethylidene)succinate l-prolinol cyclic amide esterC27H29NO5[α]D20=+270 (c 0.40, CHCl3)Source of chirality: l-prolinolAbsolute configuration: (P, S)

(1S,2S)-1-methyl-1-(4-methoxyphenyl)-4-methyl-7-methoxy-1,2-dihydronaphtalene-2,3-dicarboxylate l-prolinol cyclic amide esterC27H29NO5[α]D20=+16 (c 1.00, CHCl3)Source of chirality: l-prolinolAbsolute configuration: (1S, 2S, 2″S)