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Título

Synthesis of chiral spiroacetals from carbohydrates

AutorMartín, Ángeles ; Salazar, José A.; Suárez, Ernesto
Fecha de publicación14-jun-1996
EditorAmerican Chemical Society
CitaciónJournal of Organic Chemistry 61(12): 3999-4006 (1996)
ResumenChiral spiroacetals of the 1,7-dioxaspiro[5.5]undecane, 1,6-dioxaspiro[4.5]decane, and 1,6-dioxaspiro[4.4]nonane types have been prepared from carbohydrates in pyranose or furanose forms. The spirocyclization reaction has been accomplished from a conveniently homologated carbohydrate by an intramolecular hydrogen abstraction reaction promoted by alkoxy radicals. Thus, 2,3,4,6-tetra-O-benzyl-1-deoxy-1-(3'-hydroxypropyl)-α-d-glucopyranose (2) was photolyzed with visible light in the presence of (diacetoxyiodo)benzene and iodine to give a mixture of (1R)-(3) and (1S)-2,3,4,6-tetra-O-benzyl-1-deoxy-d-glucopyranose-1-spiro-2'-tetrahydrofuran (4). The photolysis of methyl 6-deoxy-6-(2'-hydroxyethyl)-2,3,4-tri-O-methyl-α-d-glucopyranoside (8) gave the isomeric spiroacetals methyl (5S)- (9) and (5R)-6-deoxy-5,2'-epoxy-6-ethyl-2,3,4-tri-O-methyl-α-d-glucopyranoside (10) in which the spirocenter is now located at C-5. The spiroacetals of the [5.5]undecane series: methyl (5R)- (19) and (5S)-6-deoxy-5,3'-epoxy-2,3,4-tri-O-methyl-6-propyl-β-d-glucopyranoside (20) have been prepared starting from methyl 6-deoxy-6-(3'-hydroxypropyl)-2,3,4-tri-O-methyl-β-d-glucopyranoside (18). The reaction has also been applied to hexofuranoses and 1-deoxy-1-(3'-hydroxypropyl)-2,3:5,6-di-O-isopropylidene-α-d-mannofuranose (21) gave rise to (1S)- (22) and (1R)-1-deoxy-2,3:5,6-di-O-isopropylidene-d-mannofuranose-1-spiro-2'-tetrahydrofuran (23); and 1-deoxy-1-(4'-hydroxybutyl)-2,3:5,6-di-O-isopropylidene-α-d-mannofuranose (28) to (1R)- (30) and (1S)-1-deoxy-2,3:5,6-di-O-isopropylidene-d-mannofuranose-1-spiro-2'-tetrahydropyran (32). Both spiroacetal enantiomers are formally available from the same carbohydrate.
Descripción8 pages, 1 table, 7 schemes.-- Supporting information available at: http://pubs.acs.org/doi/suppl/10.1021/jo960060g
Versión del editorhttp://dx.doi.org/10.1021/jo960060g
URIhttp://hdl.handle.net/10261/17006
DOI10.1021/jo960060g
ISSN0022-3263
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