Chemistry of Pyrido[2,1-c][1,4]oxazines, Pyrido[2,1-c][1,4]thiazines, Pyrido[1,2-a]pyrazines and Their Benzologues

Two Reaction Modes of Pyridinium 1,4-Zwitterionic Thiolates with Sulfenes: Synthesis of 3H-1,2-Dithiole 2,2-Dioxides, 1,9a-Dihydropyrido[2,1-c][1,4]thiazines, and Indolizines

“…Unexpectedly, when the reaction was performed in dichloromethane (DCM) in the presence of TEA at room temperature, 1,9a-dihydropyrido­[2,1- c ]­[1,4]­thiazine 3a was isolated as the major product in moderate yield with excellent diastereoselectivity, regardless of which substrate is excessive (see Scheme ). The exact structure of 3a was further confirmed by X-ray diffraction (XRD) analysis, which features a scarce sulfur-containing heterocyclic framework of pyrido­[2,1- c ]­[1,4]­thiazine . We speculated that 3a was derived from 1a and 2a via a stepwise [(5 + 2) – 1] (i.e., formal [5 + 1]) pathway, which was different from previous reaction modes listed in Scheme .…”

Recent Advances in the Area of Pyridodiazinium Systems Containing Bridgehead-Nitrogen Atom

“…Earlier some extended and thorough review articles on these *Address correspondence to this author at the Institute of Biomolecular Chemistry, Chemical Research Center, Hungarian Academy of Sciences, H-1025 Budapest, Pusztaszeri út 59-67, Hungary; Tel: +36-13257550; Fax: +36-13257865; E-mail: ghajos@chemres.hu and other oxa and thio analogues appeared. Thus, detailed history of chemistry of the title compounds can be found for the following ring systems: pyrido[1,2-a]pyrimidinium (b, [1,2,3]), pyrido [1,2-a]pyrazinium (c, [1,2,4]), pyrido [1,2-c]pyrimidinium (d, [1,2,5]) and pyrido [1,2-b]pyridazinium salts (e, [1,2,6]). These surveys reveal that in many cases relatively much attention has been paid to partly saturated derivatives of these cations which may have two main reasons: (i) the heteroaromatic cationic species are reactive enough in many cases to undergo transformations in which the aromatic character has been lost, (ii) some partly saturated derivatives (e.g.…”

Asymmetric Three-Component Domino Reaction: An Original Access to Chiral Nonracemic 1,3-Thiazin-2-ones

“…1,3-Thiazines A and B (Figure ) are attractive six-membered N,S -heterocyclic scaffolds for medicinal chemistry . Compounds bearing this subunit often exhibit valuable biological activities and are also used as precursors for the preparation of other heterocyclic biomolecules, such as cephalosporins or 1,4-thiazepines .…”