title: Study on the base-catalyzed reverse vinylogous aldol reaction of (4abeta,5beta)-4,4a,5,6,7,8-hexahydro-5-hydroxy-1,4a-dimethylnaphthalen-2(3H)-one under Robinson annulation conditions.
abstract: [reaction: see text] We have proposed a pathway for the base-catalyzed reverse vinylogous aldol reaction of (-)-(4abeta,5beta)-4,4a,5,6,7,8-hexahydro-5-hydroxy-1,4a-dimethylnaphthalen-2(3H)-one [(-)-8] under Robinson annulation conditions. For confirmation, 4-(2,6-dimethyl-3-oxocyclohex-1-enyl)butanal (11) and 4-(2,6-dimethyl-5-oxocyclohex-1-enyl)butanal (12), both of which potentially produce enolate I, were synthesized regioselectively. Unexpectedly, 11 gave a complex mixture, including only a trace amount of (+/-)-8 (less than 5% yield), under these basic conditions. To the contrary, 12 cleanly afforded (+/-)-8 in 66% yield. This result provides evidence for our proposed mechanism of the above reaction.
authors.affiliation: Department of Chemistry, Dartmouth College, 6128 Burke Laboratory, Hanover, New Hampshire 03755, USA.
authors.forename: Joshua N
authors.initials: JN
authors.lastname: Payette
authors.forename: Tadashi
authors.initials: T
authors.lastname: Honda
authors.forename: Hidenori
authors.initials: H
authors.lastname: Yoshizawa
authors.forename: Frank G
authors.initials: FG
authors.lastname: Favaloro
authors.forename: Gordon W
authors.initials: GW
authors.lastname: Gribble
mesh_terms: D002384:Catalysis; D015394:Molecular Structure; D009281:Naphthalenes / Q000737:chemistry*; D009930:Organic Chemicals / Q000737:chemistry*; D014753:Vinyl Compounds / Q000737:chemistry*
chemical_list: C511884:(4abeta,5beta)-4,4a,5,6,7,8-hexahydro-5-hydroxy-1,4a-dimethylnaphthalen-2(3H)-one; D009281:Naphthalenes; D009930:Organic Chemicals; D014753:Vinyl Compounds