Cycloheptanone via a Lewis acid-catalyzed cyclization of 6-heptenoyl chloride to .beta.-chlorocycloheptanone

Lewis acid promoted reactions of n-(1-phenylcyclopropyl)alkanoyl chlorides. Ring-size effects in competitive intramolecular acylation of phenyl and cyclopropyl substituents

“…After 1 h the reaction mixture was allowed to warm to room temperature, and after a reaction time of 12 h the resulting dark brown reaction mixture was again cooled in an ice bath. Following the workup procedure described for the synthesis of 2,0.32 g of a dark oil was obtained that, by GC and NMR analyses, contained 0.26 mmol (26% yield) of 3 and 0.48 mmol (48% yield) of an additional product identified as 4,4-diphenvlcycloheptanone: mp 100.5-101.5 °C; NMR (CDC13) 7.27 (10 H, s),'2.8-2.3 (2 H, m), 2.56 (4 H, s), and 2.3-1.5 (4 H, m); IR (CC14)18 3084,3062,3028,2940,2872,1702 (11) The corresponding reaction of 1 ( = 4) with aluminum chloride in benzene that contained 1.2 molar equiv of triphenylmethane produced 3 (34% yield), 4,4-diphenylcycloheptanone (31% yield), and triphenylmethanol (14% yield based on 1). Thus, hydride transfer from triphenylmethane, even in the nucleophilic benzene solvent, occurs at the expense of electrophilic substitution.…”

“…(1 , AB d, J = 7.5 Hz), 6.61 (1 , AB d, J = 7.5 Hz), 6.1-5.6 (1 H, br, phenolic OH), 3.02 (2 H, q), and 1.32 (3 H, t); IR (CC14) 3600 (free O-H), 3600-3100 (associated O-H), 3070, 2970,2940, 2880,1590,1508, 1452, 1380, 1270,1258, 1140, 1048, and 880 cm-1. 4-Phenylcycloheptanone (3). 4-(l-Phenylcyclopropyl)butanoyl chloride (0.223 g, 1.00 mmol) in 2 mL of dry methylene chloride was added to a continuously stirred, ice-bath cooled mixture of aluminum chloride (0.35 g, 2.6 mmol) in 10 mL of anhydrous methylene chloride.…”