ABSTRACT
Enantioselective nickel-catalyzed arylative cyclizations of substrates containing a Z-allylic phosphate tethered to an alkyne are described. These reactions give multisubstituted chiral aza- and carbocycles, and are initiated by the addition of an arylboronic acid to the alkyne, followed by cyclization of the resulting alkenylnickel species onto the allylic phosphate. The reversible E/Z isomerization of the alkenylnickel species is essential for the success of the reactions.
ABSTRACT
X-ray crystallography confirmed the formation, structure and relative stereochemistry of the title compound, C(15)H(19)NO(3), which contains a sterically congested four-membered azetidine ring system. The absolute configuration was determined by the use of l-arabinose as the starting material.
ABSTRACT
Primary amines with either 3,5-di-O-ditriflates of α-furanosides or 2,4-di-O-triflates of ß-pyranosides form bicyclic azetidines in high yield.
Subject(s)
Amines/chemistry , Azetidines/chemical synthesis , Glucose/chemistry , Imino Sugars/chemical synthesis , Mesylates/chemistry , Azetidines/chemistry , Cyclization , Imino Sugars/chemistry , Molecular Structure , Structure-Activity RelationshipABSTRACT
Although there are 32 6-azidoheptitols, there are only 16 homonojirimycin (HNJ) stereoisomers. Two epimeric azidoalditols derived from d-mannose allow the synthesis in water of eight stereoisomers of HNJ.
Subject(s)
1-Deoxynojirimycin/analogs & derivatives , Mannose/chemistry , 1-Deoxynojirimycin/chemical synthesis , 1-Deoxynojirimycin/chemistry , Euphorbiaceae/chemistry , Molecular Structure , StereoisomerismABSTRACT
The structure determination confirms the stereochemistry of the title compound, C(12)H(17)NO(3), which contains a four-membered azetidine ring system. The absolute configuration was determined by the use of d-glucose as the starting material. In the crystal, O-Hâ¯O and O-Hâ¯N hydrogen bonds link the mol-ecules into layers in the ab plane.
ABSTRACT
Efficient ring closure of stable crystalline 3,5-di-O-triflates of pentofuranosides with amines to form azetidines allowed preliminary evaluation of four-ring iminosugars as glycosidase inhibitors; significant and specific inhibition of nonmammalian α-glucosidases is shown by L-xylo- and L-arabino-iminosugar azetidines.
Subject(s)
Azetidines/chemistry , Enzyme Inhibitors/chemical synthesis , Glycoside Hydrolases/antagonists & inhibitors , Imino Sugars/chemical synthesis , Animals , Enzyme Inhibitors/pharmacology , Imino Sugars/pharmacology , Molecular Structure , Structure-Activity RelationshipABSTRACT
In the title compound, C(13)H(21)N(3)O(6), the six-membered ring adopts a twist-boat conformation with the azide group in the bowsprit position. The azide group is disordered over two sets of sites in a 0.642â (10):0.358â (10) ratio. The crystal structure consists of O-Hâ¯O hydrogen-bonded trimer units. The absolute configuration was determined from the use of d-mannose as the starting material.