title: Iron(III)-catalyzed Prins-type cyclization using homopropargylic alcohol: a method for the synthesis of 2-alkyl-4-halo-5,6-dihydro-2H-pyrans.
abstract: [reaction: see text] A new Prins-type cyclization between homopropargylic alcohol and aldehydes in the presence of FeX(3) to obtain 2-alkyl-4-halo-5,6-dihydro-2H-pyrans in good yield is described. Osmium-catalyzed cis dihydroxylation provided direct access to trans-2-alkyl-3-hydroxy-tetrahydro-pyran-4-ones. Anhydrous ferric halides are also shown to be excellent catalysts for the standard Prins cyclization using homoallylic alcohol. Isolation of an intermediate acetal provides substantiation of a proposed mechanism.
authors.affiliation: Instituto Universitario de Bio-Orgánica Antonio González, Universidad de La Laguna, C/Astrofísico Francisco Sánchez 2, 38206 La Laguna, Tenerife, Spain.
authors.forename: Pedro O
authors.initials: PO
authors.lastname: Miranda
authors.forename: David D
authors.initials: DD
authors.lastname: Díaz
authors.forename: Juan I
authors.initials: JI
authors.lastname: Padrón
authors.forename: Jaime
authors.initials: J
authors.lastname: Bermejo
authors.forename: Victor S
authors.initials: VS
authors.lastname: Martín