title: C2-Symmetric enantiopure ethanotethered bis(alpha,beta-butenolides) as templates for asymmetric synthesis. Application to the synthesis of (+)-grandisol.
abstract: Starting from D-mannitol, we have prepared several C(2)-symmetric ethanotethered bis(alpha,beta-butenolides) and studied their [2+2] photocycloaddition reaction with ethylene. The protective groups of the central diol unit have a noticeable influence on the facial selectivity of the cycloaddition, the bis(trimethylsilyloxy) derivatives showing the highest diastereoselectivity. A theoretical conformational analysis of the substrates in the ground state is in good agreement with the diastereofacial selectivity experimentally observed. The bis(photocycloadducts) have been converted into the enantiopure cyclobutanes formally derived from the photoreaction of ethylene with gamma-hydroxymethyl-alpha,beta-butenolide, in which only a moderate facial selectivity had been previously found. As an application of these studies, we have developed a highly efficient and stereoselective synthesis of (+)-grandisol.
authors.affiliation: Departament de Química and Unitat de Cristal.lografia, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain.
authors.forename: Pedro
authors.initials: P
authors.lastname: de March
authors.forename: Marta
authors.initials: M
authors.lastname: Figueredo
authors.forename: Josep
authors.initials: J
authors.lastname: Font
authors.forename: Javier
authors.initials: J
authors.lastname: Raya
authors.forename: Angel
authors.initials: A
authors.lastname: Alvarez-Larena
authors.forename: Juan F
authors.initials: JF
authors.lastname: Piniella
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives; D002384:Catalysis; D020650:Combinatorial Chemistry Techniques; D005663:Furans / Q000737:chemistry*; D007202:Indicators and Reagents; D008353:Mannitol / Q000737:chemistry*; D008962:Models, Theoretical; D008968:Molecular Conformation; D015394:Molecular Structure; D013237:Stereoisomerism; D013729:Terpenes / Q000138:chemical synthesis*
chemical_list: D005663:Furans; D007202:Indicators and Reagents; D013729:Terpenes; D008353:Mannitol; C004511:butenolide; C013009:grandisol; D015107:4-Butyrolactone