title: Regiocontrolled ring opening of monoprotected 2,3-epoxy-1,4-diols using alkynyl aluminum reagents. Synthesis of differentially monoprotected alkynyl triol derivatives.
abstract: The regioselectivity of the epoxide ring opening reaction of cis and trans TIPS-monoprotected 2,3-epoxy-1,4-diols with diethylalkynyl aluminum reagents was studied. Alane and alanate conditions in toluene or dichloromethane were explored. The alkynyl attack at the C2 epoxide carbon was favored for both, the alane and alanate conditions in toluene, while in dichloromethane the C3 attack was preferred. The best regioselectivities were obtained using the alanate conditions in toluene. This methodology provides access to differentially monoprotected alkynyl triols with high diastereoselectivity. These compounds are useful building bocks for polypropionate synthesis and are precursors for the introduction of the hydroxymethyl moiety found in some polyketide systems.
authors.affiliation: Department of Chemistry, University of Puerto Rico, PO Box 23346, San Juan, PR 00931-3346 Fax:1-787-759-6885.
authors.forename: José A
authors.initials: JA
authors.lastname: Prieto
authors.affiliation: Department of Chemistry, University of Puerto Rico, PO Box 23346, San Juan, PR 00931-3346 Fax:1-787-759-6885.
authors.forename: Jaileen Rentas
authors.initials: JR
authors.lastname: Torres
authors.affiliation: Department of Chemistry, University of Puerto Rico, PO Box 23346, San Juan, PR 00931-3346 Fax:1-787-759-6885.
authors.forename: Raul
authors.initials: R
authors.lastname: Rodríguez-Berrios
keywords: alkynyl aluminum; epoxide cleavage; epoxy alcohols; polypropionates; propargylic alkynol