Sergei G. Zlotin

C2-Symmetric diamines and their derivatives as promising organocatalysts for asymmetric synthesis

The review is devoted to the application of C2-symmetric diamines and their derivatives as organocatalysts for asymmetric reactions (aldol, Michael, Mannich, Diels–Alder reactions, desymmetrization, allylation, etc.). Amino acid derivatives, di- and polyamides (sulfamides), bisureas, bisthioureas, bisamidines and bisguanidines are considered. Significant attention is given to the effect of the catalyst structure on the mechanism of catalytic action. Successful applications of such catalysts in enantioselective synthesis of chiral biologically active compounds are summarized. The bibliography includes 181 references.

(1,2-Diaminoethane-1,2-diyl)bis(N-methylpyridinium) Salts as a Prospective Platform for Designing Recyclable Prolinamide-Based Organocatalysts

A new efficient and highly recyclable organocatalyst has been developed for asymmetric cross-aldol reactions under neat conditions in ketone-ketone, ketone-aldehyde, and aldehyde-aldehyde systems. The catalyst features two prolinamide fragments and a C2-symmetrical (1,2-diaminoethane-1,2-diyl)bis(N-methylpyridinium) group. The catalyst retained high activity and excellent stereoselection over the operating period of more than 830 h (25 cycles). An ab initio theoretical investigation explained the absolute configuration of the products and different stereoinduction levels for designed diastereomeric organocatalysts.

Ionic Liquids—Advanced Reaction Media for Organic Synthesis

Abstract The advantages in the application of ionic liquids as reaction media in organic synthesis, i.e., in the preparation of chromane derivatives, substituted pyrazines, 4-aminofuran-2(5H)-ones, or in bromination of Levulinic acid or dehydration of alcohols, saccharides, and polysaccharides, have been demonstrated on several examples. Ionic liquids with Brønsted acidity have been shown to possess catalytic activity and provide access to convenient technologies for the preparation of various useful compounds.

PALLADIUM-CATALYZED REACTION OF BROMINE- AND IODINE-CONTAINING ISOTHIAZOLES WITH OLEFINS

Abstract3-Bromo-4-alkenylisothiazoles were synthesized by the reaction of 3-bromo-4-iodoisothiazole with olefins in the presence of palladium acetate

Synthesis of 5-bromo-4-dibromoamino-3-phenylisothiazole and its light-induced conversion into 3,7-diphenylbisisothiazolo[4,5-b:4′,5′-e]pyrazine

When irradiated with UV light, 5-bromo-4-dibromoamino-3-phenylisothiazole is converted into 3,7-diphenylbisisothiazolo[4,5-b:4′,5′-e]pyrazine andN,N′-bis(5-bromo-3-phenylisothiazol-4-yl)diazene.

Light-induced synthesis of 3,7-disubstituted bisisothiazolo[4,5-b:4′,5′-e]pyrazines from 3-substituted 4-dibromoamino-5-haloisothiazoles

A new procedure was developed for the synthesis of 3,7-disubstituted bisisothiazolo[4,5-b:4′,5′-e]pyrazines from 3-substituted 4-dibromoamino-5-haloisothiazoles under UV irradiation.N,N′-Bis(5-haloisothiazol-4-yl)diazenes were obtained as by-products.

Chiral Ionic Liquid/ESI-MS Methodology as an Efficient Tool for the Study of Transformations of Supported Organocatalysts

An efficient approach to the study of deactivation pathways of chiral organocatalysts in asymmetric Michael reactions by modifying original catalysts with ionic-liquid fragments followed by the electrospray ionization mass spectrometry analysis of recovered catalyst samples has been proposed.

New regiospecific methods for the synthesis of N′-cyanodiazene N-oxides

New regiospecific methods have been developed for the synthesis of aliphatic, aromatic, and heterocyclic N′-cyanodiazene N-oxides based on the reactions of nitroso compounds with a system containing the sodium salt of cyanamide and tert-butyl hypochlorite and with a system containing cyanamide and dibromoisocyanurate.

Alkylation of 2,3,6,11-tetrahydroanthra[2,1-d]isothiazole-3,6,11-trione and its S-oxide

The reactions of 2,3,6,11-tetrahydroanthra[2,1-d]isothiazole-3,6,11-trione with dimethyl sulfate, benzyl chloride, and allyl bromide afforded the corresponding 2-alkyl-2,3,6,11-tetrahydroanthra[2,1-d]isothiazole-3,6,11-triones and 3-(alkoxy)-6,11-dihydroanthra[2,1-d]isothiazole-6,11-diones. The reactions of 2,3,6,11-tetrahydroanthra[2,1-d]isothiazole-3,6,11-trione and its S-oxide with a formaldehyde—secondary amine system yielded 2-[(alkylamino)methyl]-2,3,6,11-tetrahydroanthra[2,1-d]isothiazole-3,6,11-triones and 2-[(alkylamino)methyl]-3,6,11-trioxo-2,3,6,11-tetrahydroanthra[2,1-d]isothiazole 1-oxides, respectively.

Synthesis of 3-methoxy-5-oxo-6-phenyl-5,6-dihydro-4h-isothiazolo[5,4-b]-1,4-thiazine 7,7-dioxide, the first representative of a new heterocyclic system

When treated with an excess of MeONa in DMF, 5-benzylsulfonyl-3-chloro-4-methoxycarbonylaminoisothiazole undergoes cyclization into 3-methoxy-5-oxo-6-phenyl-5,6-dihydro-4H-isothiazolo[5,4-b]-1,4-thiazine 7,7-dioxide, the first representative of a new heterocyclic system. The starting 5-benzylsulfonyl-3-chloro-4-methoxycarbonylaminoisothiazole was prepared by the reaction of 5-benzylsulfonyl-4-carbamoyl-3-chloroisothiazole with PhI(OAc)2 in methanol.