Single-Pot Preparation of 4-Amino-2-(het)aryl-5-Substituted Thiazoles Employing Functionalized Dithioesters as Thiocarbonyl Precursors.

An effective, diversity oriented, one-pot reaction of 4-amino-2-(het)aryl/alkyl-5-functionalized thiazoles has been disclosed, utilizing aryl/heteroaryl/alkyl dithioesters as thiocarbonyl coupling partners in a modified Thorpe-Ziegler type cyclization. The reaction proceeds at room temperature, under mild conditions, in excellent yields, displaying broad functional group compatibility at 2 and 5 positions of thiazoles. This synthetic strategy has been further expanded for the one-pot construction of two highly potent tubulin polymerization inhibitors, i.e., 2-(het)aryl-4-amino-5-(3,4,5-trimethoxyaroyl) thiazoles, in high yields.

Reaction of 1,3-Bis(het)arylmonothio-1,3-diketones with Sodium Azide: Regioselective Synthesis of 3,5-Bis(het)arylisoxazoles via Intramolecular N-O Bond Formation.

An efficient new synthesis of 3,5-bis(het)arylisoxazoles, involving the reaction of 1,3-bis(het)arylmonothio-1,3-diketones with sodium azide in the presence of IBX catalyst, has been reported. The reaction proceeds at room temperature in high yields and is applicable to a broad range of substrates including the synthesis of 5-methyl-3-arylisoxazoles, a key subunit present in several ß-lactamase-resistant antibiotics. A probable mechanism for the formation of isoxazoles has been suggested. A few of the 5-styryl/arylbutadienyl-3-(het)arylisoxazoles have also been synthesized by reacting the corresponding 1-(het)aryl-1-(methylthio)-4-(het)arylidene-but-1-en-3-ones with sodium azide at higher temperatures. The reaction of ß-ketodithioesters with sodium azide is shown to furnish ß-ketonitriles in good yields.

Aza-Annulation of 1,2,3,4-Tetrahydro-ß-carboline Derived Enaminones and Nitroenamines: Synthesis of Functionalized Indolizino[8,7-b]indoles, Pyrido[1,2-a:3,4-b']diindoles, Indolo[2,3-a]quinolizidine-4-ones and Other Tetrahydro-ß-carboline Fused Heterocycles.

Aza-annulation of novel 1,2,3,4-tetrahydro-ß-carboline derived enaminones and nitroenamines with various 1,2- and 1,3-bis electrophiles, such as oxalyl chloride, maleic anhydride, 1,4-benzoquinone, 3-bromopropionyl chloride, itaconic anhydride, and imines (from formaldehyde and primary amines), has been investigated. These methodologies provide simple one-step pathways for efficient construction of highly functionalized tetrahydro-ß-carboline 1,2-fused, five- and six-membered heterocyclic frameworks, such as indolizino[8,7-b]indoles, pyrido[1,2-a:3,4-b']diindoles, indolo[2,3-a]quinolizidines, and pyrimido[1',6':1,2]pyrido[3,4-b]indoles, which are core structures of many naturally occurring indole alkaloids with diverse bioactivity.

Regioselective synthesis of 2-chloroquinoline based ethyl 4-(3- hydroxyphenyl)-2,7,7-trimethyl-5-oxo-1,4,5,6,7,8-hexahydroquinoline-3- carboxylates and their in-silico evaluation against P. falciparum lactate dehydrogenase.

The reaction of various substituted 2, 4-dichloroquinolines with ethyl 4-(3-hydroxyphenyl)- 2,7,7-trimethyl-5-oxo-1,4,5,6,7,8-hexahydroquinoline-3-carboxylate was carried out in the presence of K2CO3 as a mild and efficient base at controlled temperature leading to novel 2-chloroquinoline based polyhydroquinoline with high regioselectivity. All the synthesized compounds were characterized using IR, NMR, Mass spectral data and then subjected to an in-silico analysis against P. falciparum lactate dehydrogenase.