Rakeshwar Bandichhor

B,O-chelated azadipyrromethenes as near-IR probes.

Complementary synthetic routes to a new class of near-IR fluorophores are described. These allow facile access (four synthetic steps) to the core fluorophore and substituted derivatives with emissions between 740 and 780 nm in good quantum yields.

Lipid diffusion from single molecules of a labeled protein undergoing dynamic association with giant unilamellar vesicles and supported bilayers.

It is demonstrated that single-molecule tracking of a fluorescently labeled protein undergoing transient binding to model membranes presents a useful method of obtaining fluid properties. The labeled ACBP protein was tracked during its binding to free-standing giant unilamellar vesicles (GUVs) and supported bilayers prepared from the GUVs in the same environment. The analysis of images that are blurred as a result of fast probe diffusion was discussed. An examination of the lateral diffusion trajectories revealed a homogeneous diffusion on the top segments of the GUVs with D = 6.9 +/- 0.3 microm(2)/s. The supported bilayer experiments revealed two diffusion processes, one with Df = 3.1 +/- 0.4 microm(2)/s and the other with Ds = 0.078 +/- 0.001 microm(2)/s. The 2-fold difference in the lipid bilayer mobility for the free-standing and fast components in the supported bilayers is attributed to the known effect of frictional coupling with the solid support. The slow mobile fraction in the bilayer is suggested to be associated with the migration of pore-like structures, originating from the interaction of the membrane with the glass support.

Synthesis of novel therapeutic agents for the treatment of multiple sclerosis: a brief overview.

Multiple sclerosis (MS) often results in chronic inflammatory and autoimmune disorders, and recent developments in understanding the disease pathogenesis has lead to newer therapeutic options for the treatment of the disease. The development of small molecule drugs with improved efficacy, better tolerability, and oral administration has received a new impetus with the discovery of newer classes of drugs. In this review, we have summarized the hitherto known synthetic strategies of fingolimod, laquinimod, cladribine, and teriflunomide reported in the literature which are the key small molecules and the first oral drug candidates for MS in various stages of clinical development or have been launched in the market.

Alternative Total Synthesis of (−)-Galanthamine Hydrobromide

Abstract An alternative total synthesis of (−)-galanthamine (1) hydrobromide, employing ecofriendly amidation, oxidative coupling, and classical resolution strategies is accomplished.

Practical, asymmetric route to sitagliptin and derivatives: development and origin of diastereoselectivity.

The development of a practical and scalable process for the asymmetric synthesis of sitagliptin is reported. Density functional theory calculations reveal that two noncovalent interactions are responsible for the high diastereoselection. The first is an intramolecular hydrogen bond between the enamide NH and the boryl mesylate S=O, consistent with MsOH being crucial for high selectivity. The second is a novel C–H···F interaction between the aryl C5-fluoride and the methyl of the mesylate ligand.

Application of [3 + 2]-Cycloaddition in the Synthesis of Valdecoxib

Abstract A large scale synthesis of valdecoxib 1 is described. Our work features potential application of [3 + 2]-dipolar cycloaddition involving enamine and in situ–generated nitrile oxide derivatives. GRAPHICAL ABSTRACT

Asymmetric reduction of a key intermediate of eslicarbazepine acetate using whole cell biotransformation in a biphasic medium

A whole-cell mediated asymmetric reduction of oxcarbazepine 1 to S-licarbazepine 2, a key intermediate in the synthesis of Eslicarbazepine acetate, was achieved using the yeast strain Pichia methanolica 103660. The reduction was carried out in a biphasic system consisting of (1 : 1) de-ionized water and hexane. This organism catalyzed the reaction to yield the S-enantiomer 2 with excellent conversion (>98%) and enantiomeric excess (ee > 98%) within 24 h of incubation.

Synthesis of All Enantiomerically Pure Diastereomers of Aprepitant

Syntheses of all eight enantiomerically pure diastereomers of aprepitant and assignment of absolute configuration at newly generated stereocenters by NMR and x-ray crystallographic analysis were achieved.

Asymmetric Synthesis of (S,S,S)-2-Aza-bicyclo-[3.3.0]-octane-3-carboxylic Acid Benzyl Ester: Formal Synthesis of Ramipril

Abstract An asymmetric synthesis of (S,S,S)-2-aza-bicyclo-[3.3.0]-octane-3-carboxylic acid benzyl ester 2 as an intermediate of angiotensin converting enzyme (ACE) inhibitor, ramipril 1, is described.

Practical synthesis of fingolimod from diethyl acetamidomalonate

A facile six-step synthesis of fingolimod, starting from readily available and inexpensive starting material diethyl acetamidomalonate, in very good yield is demonstrated.