Govindaraju Karthik

Dual Behavior of Isatin-Based Cyclic Ketimines with Dicarbomethoxy Carbene: Expedient Synthesis of Highly Functionalized Spirooxindolyl Oxazolidines and Pyrrolines

A highly stereo-, regio-, and chemoselective method has been devised for the synthesis of a wide range of spirooxindolyl oxazolidines via an intermolecular 1,3-dipolar cycloaddition of carbonyl ylides generated from dimethyl diazomalonate and aromatic aldehydes, with cyclic ketimines using 5 mol % of Rh2(OAc)4 under mild conditions. Similarly, highly functionalized spirooxindolyl pyrrolines have also been prepared through 1,3-dipolar cycloaddition of azomethine ylides generated from dimethyl diazomalonate and cyclic ketimines, with dimethyl acetylenedicarboxylate.

Three isostructural solvates of a tetrahydrofurochromenone derivative

Isostructurality is more likely to occur in multicomponent systems. In this context, three closely related solvates were crystallized, namely, benzene (C27H21BrO6·C6H6), toluene (C27H21BrO6·C7H8) and xylene (C27H21BrO6·C8H10) with methyl 3a-acetyl-3-(4-bromophenyl)-4-oxo-1-phenyl-3,3a,4,9b-tetrahydro-1H-furo[3,4-c]chromene-1-carboxylate, and their crystal structures determined. All three structures belong to the same space group (P-1) and display similar unit-cell dimensions and conformations, as well as isostructural crystal packings. The isostructurality is confirmed by unit-cell and isostructural similarity indices. In each solvate, weak C-H...O and C-H...π interactions extend the molecules into two-dimensional networks, which are further linked by C-H...Br and Br...Br interactions into three-dimensional networks. The conformation of the core molecule is predominantly responsible for governing the isostructurality.