177995-66-3Relevant academic research and scientific papers
Synthesis of Chiral Spiroacetals from Carbohydrates
Martin, Angeles,Salazar, Jose A.,Suarez, Ernesto
, p. 4489 - 4492 (1995)
Optically active spiroacetals are prepared from carbohydrates with an intramolecular hydrogen abstraction reaction as the key step.Both spiroacetal enantiomers are formally available from the same sugar.
Synthesis of chiral spiroacetals from carbohydrates
Martin, Angeles,Salazar, Jose A.,Suarez, Ernesto
, p. 3999 - 4006 (2007/10/03)
Chiral 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-tetraO-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-glucopvranose-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-/a-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-deoxy2,3:5,6-di-O-isopropylidene-D-mannofuranose-1-spiro-2′- tetrahydropyran (32). Both spiroacetal enantiomers are formally available from the same carbohydrate.
