ABSTRACT
The ß-selective phenylation of benzyl and boronate protected 1,6-anhydroglucose and the direct phenylation of unprotected 1,6-anhydroglucose (10), pretreated with i-Bu2AlH, i-Bu3Al, Et3Al, Me3Al, or n-octyl3Al, with triphenylalane or aryl(chloro)alanes is reported. The utility of the unprotected version of the method is demonstrated by the synthesis of the SGLT2 inhibitor, canagliflozin (1a), from commercially available 10 in one C-C bond-forming step. This approach circumvents the need for conventional protecting groups, and therefore no formal protection and deprotection steps are required.
Subject(s)
Canagliflozin/chemical synthesis , Glucose/analogs & derivatives , Glucose/chemistry , Organometallic Compounds/chemistry , Canagliflozin/chemistry , Catalysis , Hypoglycemic Agents , Molecular StructureABSTRACT
The stereoselective arylation of hydroxy protected 1,6-anhydro-ß-d-glucose with arylalanes to provide ß-C-arylglucosides is reported. Modification of triarylalanes, Ar3Al, with strong Brønsted acids (HX) or AlCl3 produced more reactive arylating agents, Ar2AlX, while the incorporation of alkyl dummy ligands into the arylating agents was also viable. Me3Al and i-Bu2AlH were found useful in the in situ blocking of the C3-hydroxyl group of 2,4-di-O-TBDPS protected 1,6-anhydroglucose. The utility of the method was demonstrated by the synthesis of the SGLT2 inhibitor, canagliflozin.
ABSTRACT
NHC-catalyzed oxidations using carbon dioxide as the stoichiometric oxidant have been carefully investigated. These studies support a secondary role of CO(2) in suppressing side reactions and exogenous oxygen as the actual oxidant.
Subject(s)
Aldehydes/chemistry , Carbon Dioxide/chemistry , Methane/analogs & derivatives , Catalysis , Methane/chemistry , Molecular Structure , Oxidation-ReductionABSTRACT
Alpha'-hydroxyenones undergo clean, catalytic amidations with amines promoted by the combination of an N-heterocyclic carbene and 1,2,4-triazole.
Subject(s)
Amides/chemical synthesis , Indicators and Reagents/chemistry , Acylation , Amides/chemistry , Catalysis , Heterocyclic Compounds/chemistry , Molecular Structure , Triazoles/chemistryABSTRACT
N-heterocyclic carbene-catalyzed reactions of alpha,beta-unsaturated aldehydes and a variety of electrophiles allow the facile preparation of a diverse array of annulation products including trisubstituted cyclopentenes, gamma-lactams, and bicyclic beta-lactams. The substrate scope of these reactions, however, is limited by the difficulties of preparing the starting alpha,beta-unsaturated aldehydes. We now report that alpha'-hydroxyenones, which can be prepared in a single convenient step from aromatic and heteroaromatic aldehydes, can serve as efficient surrogates for enals in the annulation reactions. This protocol allows the facile preparation and use of substrates bearing nitrogen heterocycles. These reagents have also allowed us to demonstrate that, in contrast to other classes of aldehydes, the formation of the Breslow intermediate from enals and N-heterocyclic carbenes is irreversible under the reaction conditions.