Pd-catalyzed ring opening of oxa- and azabicyclic alkenes with aryl and vinyl halides: efficient entry to 2-substituted 1,2-dihydro-1-naphthols and 2-substituted 1-naphthols.
An efficient syntheses of 2-substituted 1,2-dihydro-1-naphthols and 2-substituted 1-naphthols has been developed that involves the sequential palladium-catalyzed ring opening of oxabicyclic alkenes with aryl and vinyl halides followed by oxidation of with IBX. In the first step of the sequence, a combination of Pd(OAc)2, PPh3, Zn, and PMP in dry DMF was employed to catalyze the ring opening of 7-oxabenzonorbornadienes with aryl and vinyl halides to afford the corresponding cis-2-substituted 1,2-dihydronaphthols in good to excellent yields. These reactions occurred under very mild conditions with a variety of aryl halides bearing electron-withdrawing or -donating groups. Similarly, a 7-azabenzonorbornadiene substituted with an electron-withdrawing group on the nitrogen atom underwent facile ring-opening reaction with aryl halides to provide cis-2-substituted (1,2-dihydro-1-naphthyl)carbamates in excellent yields. Oxidation of the intermediate 1,2-dihydro-1-naphthols using IBX yielded the corresponding 2-substituted 1-naphthols in good to excellent yields.
Chen
Chi-Li
CL
Department of Chemistry and Biochemistry, University of Texas, Austin, Texas 78712, USA.
Martin
Stephen F
SF
D000475:Alkenes / Q000737:chemistry*; D001952:Bridged-Ring Compounds / Q000737:chemistry*; D002384:Catalysis; D006846:Hydrocarbons, Halogenated / Q000737:chemistry*; D015394:Molecular Structure; D009284:Naphthols / Q000138:chemical synthesis* / Q000737:chemistry; D010165:Palladium / Q000737:chemistry*; D013237:Stereoisomerism; D014753:Vinyl Compounds / Q000737:chemistry*
D000475:Alkenes; D001952:Bridged-Ring Compounds; D006846:Hydrocarbons, Halogenated; D009284:Naphthols; D014753:Vinyl Compounds; D010165:Palladium