Crystal structures, chiralities and photochemistry of two polymorphs of L -prolinolium α-adamantylacetophenone-p-carboxylate

The absolute stereochemical course of the photochemical rearrangement reactions of α-adamantylacetophenones has been studied by crystal structure analyses of two polymorphs of L-prolinolium α-adamantylacetophenone-p-carboxylate and of a crystal containing the major photoproduct, and by correlation of the crystal structure data with photochemical behaviour. Crystal data are: T=295 K, Cu Kα, λ=1.54178 A. L-Prolinolium α-adamantylacetophenone-4-carboxylate, C 24 H 33 NO 4 , C 5 H 12 -NO + .C 19 H 21 O 3 - , M r =399.53; needle form, P2 1 2 1 2 1 , a=17.266 (2), b=19.292 (3), c=6.3739 (9) A, Z=4, R=0.041 for 1583 reflections with I>3σ(1); plate form, P2 1 2 1 2 1 , a=11.798 (1), b=43.563 (3), c=8.4434 (8) A, Z=8 (two molecules per asymmetric unit), R=0.056 for 3565 reflections