Stereoselectivities in AgBF4-catalyzed and photoinduced phenyl-rearrangement of 2-chloropropiophenone

(S)-2-Phenylpropionic acid was stereoselectively obtained by the AgBF4- cat alyzed phenyl-rearrangement of (S)-2-chloropropiophenone dimethyl acetal, w hile the photoirradiation of (S)- or (R)-2-chloropropiophenone afforded par tially racemized (S)- or (R)-2-phenylpropionic acid, respectively. An intra molecular S(N)2 mechanism is suggested for the former rearrangement. The la tter result is indicative of the intervention of an ion or radical intermed iate in the photoinduced phenyl-rearrangement. (C) 1998 Elsevier Science Lt d. All rights reserved.