title: Montmorillonite K-10 clay-catalyzed Ferrier rearrangement of 2-C-hydroxymethyl-d-glycals, 3,4,6-tri-O-alkyl-d-glycals, and 3,4-(dihydro-2H-pyran-5-yl)methanol: a few unexpected domino transformations.
abstract: Montmorillonite K-10 clay-catalyzed substitution reactions of 3,4,6-tri-O-alkyl-2-C-hydroxymethyl-d-glycals, 3,4,6-tri-O-acetyl-d-glycals, 3,4,6-tri-O-alkyl-d-glycals, and 3,4-(dihydro-2H-pyran-5-yl)methanol with a few alcohols and phenols are described. The reactions of 2-C-hydroxymethyl-d-glycals with phenols were similar to those of 2-C-acetoxymethyl-d-glycals and afforded pyrano[2,3-b]benzopyrans. This montmorillonite K-10 clay-catalyzed transformation is facile both under ambient (Method 1) and microwave conditions (Method 2). Ferrier rearrangement of 3,4-(dihydro-2H-pyran-5-yl)methanol with p-cresol, 2,6-xylenol, and ethanol led to totally unexpected transformations. Reaction of 2-C-hydroxymethyl-d-galactal with 2,6-dimethylphenol in the presence of montmorillonite K-10 led to a novel domino transformation affording 4-(5',6'-dihydro-4H-pyran-3'-ylmethyl)-2,6-dimethylphenol. In contrast, 3,4,6-tri-O-acetyl-d-glucal furnished the Ferrier rearrangement product, 2,6-dimethylphenyl 4,6-di-O-acetyl-2,3-dideoxy-α-d-erythro-hex-2-enopyranoside. Also, isomerization of 3,4,6-tri-O-alkyl-d-glycals to products of allylic rearrangement, 2,3-unsaturated-O-glycosides in good yields is reported.
authors.affiliation: Shasun Research Centre, Chennai, Tamil Nadu, India.
authors.forename: Elumalai
authors.initials: E
authors.lastname: Kumaran
authors.forename: Meenakshisundaram
authors.initials: M
authors.lastname: Santhi
authors.forename: Kalpattu K
authors.initials: KK
authors.lastname: Balasubramanian
authors.forename: Shanmugasundaram
authors.initials: S
authors.lastname: Bhagavathy
mesh_terms: D001546:Bentonite / Q000737:chemistry*; D002241:Carbohydrates / Q000737:chemistry*; D002384:Catalysis; D006027:Glycosides / Q000737:chemistry; D000432:Methanol / Q000031:analogs & derivatives / Q000737:chemistry*; D015394:Molecular Structure; D010636:Phenols / Q000737:chemistry
chemical_list: D002241:Carbohydrates; D006027:Glycosides; D010636:Phenols; C503188:montmorillonite K-10; D001546:Bentonite; D000432:Methanol