A facile and efficient approach for the synthesis of a variety of acridines via the tandem coupling/cyclization of substituted 2-bromobenzaldehydes and anilines is described. The reaction can be accomplished with ease in the presence of a catalytic amount of Pd2(dba)3 and diphosphine ligand dppf, providing a broad range of substituted acridines in good to excellent yields (up to 99%). The Lewis...

In order to elucidate the reaction mechanism of the cyclization between an ethynyl group and an imino group at the ortho-position on an aromatic ring to afford isoquinolines, reaction of 2-ethynylbenzaldehydes under various conditions was examined. It is concluded that reaction proceeds via an ionic process and the isoquinoline 4-hydrogen atom derives from the solvent. In addition, it was found...

A novel and convenient approach to the synthesis of various phosphorated indolines via a copper-catalyzed radical cascade cyclization reaction has been developed. The reaction employs cheap copper as the catalyst and K2S2O8 as the oxidant under mild conditions. Various alkenes and P-radical precursors are compatible with this transformation. Preliminary mechanistic studies reveal that the addit...

Silica ferric hydrogensulfate is an efficient heterogeneous catalyst for the cyclization of 2- aminochalcones to the corresponding 2,3-dihydroquinolin- 4(1H)-ones. This intramolecular aza Michael reaction was carried out in high yields using chalcones bearing of electron donating and electron withdrawing groups. The catalyst is reusable without significant decreases in its activity after four t...

Stereoselective formal synthesis of (+)-allokainic acid was accomplished starting from L-glutamate by using a thiol-mediated acyl radical cyclization as a key step. The cyclization of a formylalkenoate proceeded in a highly diastereoselective manner to give trans-4,5-disubstituted pyrrolidin-3-one without the production of the cis-isomer. The pyrrolidinone was then converted into the establishe...

Crystal Structure, 1,2,4-Thiadiazole, Intramolecular Cyclization The title compound was obtained in 82% yield by the intramolecular cyclization of 4BrC6H4C(NSCCl3)[N(SiMe3)2] in CH2CI2 at 23°C. It crystallizes in the triclinic system, space group PI, a = 7.957(3) Ä, b = 10.864(5) A, c = 5.625(1) A, a = 95.94(3)°, ß = 97.79(2)°, 7 = 100.72(3)°, V = 469.2(3) A3, and Z 2. The bond lengths of the p...

Previously unstudied dibenzoindolo[3,2-b]carbazoles have been prepared by two-directional, phase tag-assisted synthesis utilizing a connective-Pummerer cyclization and a SmI2-mediated tag cleavage-cyclization cascade. The use of a phase tag allows us to exploit unstable intermediates that would otherwise need to be avoided. The novel materials were characterized by X-ray, cyclic voltammetry, UV...

A flexible and practical protocol for the asymmetric synthesis of renieramycin-type antitumor alkaloids is described, in which the stereoselective Pictet-Spengler cyclization of amino ester 16 and aldehyde 15 by regulating temperature and the automatic lactamization after N-deprotection of the cyclization product are exploited to rapidly construct the common pentacyclic framework. (-)-Renieramy...

A miniflow system for oxidative cyclization of alkenols with Oxone was developed. Thus, the oxidative cyclization of (Z)- and (E)-alkenols in i-PrOH with an aqueous solution of Oxone proceeded smoothly and safely in a PTFE tube without any exogenous catalytic species, and was subsequently quenched in a flow-reaction manner to afford the corresponding furanyl and pyranyl carbinols quantitatively...

The n-butyramido, isobutyramido, benzamido, and furancarboxamido functions profoundly modulate the electronics of the stilbene olefinic and NH groups and the corresponding radical cations in ways that influence the efficiency of the cyclization due presumably to conformational and stereoelectronic factors. For example, isobutyramido- stilbene undergoes FeCl(3) promoted cyclization to produce on...