Trimethylsilylnitrate: a useful reagent for direct synthesis of 2-deoxy-O-glycosides from glycals

Trimethylsilylnitrate acts as a useful reagent for the addition of alcohols to glycals forming 2-deoxy-O-glycosides in good to excellent yields

Functionalization of Glycals Leading to 2-Deoxy-O-glycosides, Aminosugars, Nitrosugars and Glycosidase Inhibitors: Our Experience

Glycals have been transformed into a variety of functionalized substrates which have been found to be useful in synthesizing some aminosugars, N-glycopeptides, nitrosugars and some iminosugars which are potential glycosidase inhibitors. An account of work that has been done in our laboratory is briefly discussed here

Ytterbium triflate (and trimethylsilyl triflate) catalyzed isomerization of glycidic esters to α-hydroxy-β,γ-unsaturated esters and their conversion into cyclopentanoids using Johnson-Claisen rearrangement

A variety of glycidic esters undergo smooth isomerization to the corresponding α-hydroxy-β, γ-unsaturated esters upon reaction with Yb(OTf)3 or TMSOTf. These α-hydroxy-β, γ-unsaturated esters undergo Johnson-Claisen rearrangement to appropriately substituted diesters, some of which are converted into cyclopentanoids

Palladium catalysed allylic substitution via in situ activation of allylic alcohols

In-situ activation of a variety of allylic alcohols by hexachlorophosphazene (or oxalyl chloride) followed by Pd(0) catalysed reactions with lithio dimethyl malonate leads to the regio and stereoselective alkylations in god yields

Facile aza-Claisen rearrangement of glycals: application in the synthesis of 1-deoxy-L-iminosugars

2-C-Methylene-N-glycosyl amides have been obtained from 2-(hydroxymethyl)glycals through a facile aza-Claisen rearrangement. This rearrangement has also been utilized in the synthesis of L-allo-deoxynojirimycin, a moderate inhibitor of human lysosomal α-mannosidase (IC<SUB>50</SUB>=64 μM), and two new C-5-(hydroxymethyl) analogues of L-altro-deoxynojirimycin and L-ido-deoxynojirimycin

Synthesis of C-2 methylene O- and C-glycosides and sugar derived α-methylene-δ-valerolactones from C-2-acetoxymethyl glycals

C-2-Methylene O- and C-glycosides are readily synthesized from C-2-acetoxymethyl glycals using Nafion-H®, montmorillonite K-10, LiClO4 (0.07 M) in dichloromethane and Pd(PPh3)4 as catalysts. Exclusive α or β selectivities have been observed with various primary, secondary and tertiary alcohols, phenols and diethyl malonate. Further, C-2-acetoxymethyl glycals are also converted into corresponding α-methylene-δ-valerolactones in good yields in one step using m-CPBA in the presence of BF3·Et2O

Synthesis of (-)-coniine and (-)-pipecoline using ruthenium catalyzed ring closing metathesis

Ring closing metathesis employing the well-known Grubbs' ruthenium catalyst has been used as the key step in the synthesis of piperidine alkaloids, (-)-coniine and (-)-pipecoline, and the asymmetric induction has been performed by using (R)-α-methyl benzylamine as an auxiliary

A simple synthesis of 3-nitrocycloalkenones and their acetals

Synthesis of 3-nitrocyclohexenone and 3-nitrocycloheptenone and their acetals in described starting from cyclohexanone and cycloheptanone respectively

Synthesis of conformationally constrained C-glycosyl α- and β-amino acids and sugar-carbamino sugar hybrids via Diels-Alder reaction

Sugar-derived dienes undergo Diels-Alder reactions with methyl α-nitro acrylate and ethyl β-nitro acrylate to form the corresponding cycloadducts which have been converted into conformationally constrained C-glycosyl α- and β-amino acids. Further, these β-amino acids are converted into sugar-carbamino sugar hybrid molecules

Zeolite (H-ZSM 5) catalysed regio and stereoselective reduction of 2,3-epoxy alcohols to 1,2-diols and vinylic epoxides to homoallylic alcohols with sodium cyanoborohydride

A variety of 2,3-epoxy alcohols and vinylic epoxides (having the epoxide moieties at the terminal positions) undergo reduction with zeolite H-ZSM 5/NaCNBH<SUB>3</SUB> combination of reagent system in refluxing dichloroethane to give 1,2-diols and homoallylic alcohols in moderate to good yields. Under these conditions acid sensitive groups such as an acetal and a THP ether are not affected which indicates the mildness of the reaction conditions