Isoxazoles are important five-membered aromatic heterocycles in organic chemistry. Recently, many exciting advances in the synthesis and functionalization of isoxazoles have been reported. New transition metal-catalyzed reactions have resulted in the development of attractive and highly efficient synthetic approaches to densely functionalized isoxazoles. Complete control of regioselectivity can be achieved on the basis of a judicious choice of metal catalyst and reaction partners using dipolar cycloaddition and cycloisomerization reactions, while more recent studies have focused on the site-selective functionalization of isoxazoles via CH functionalization. New strategies for the use of isoxazoles as scaffolding templates in asymmetric synthesis have emerged, thus opening new prospects for the synthesis of enantioenriched motifs under the conditions that are orthogonal to other transformations. In this review, recent advances involving the synthesis and reactivity of isoxazoles are summarized. The review covers the period from January 2005 to June 2015.

Recent Developments in the Synthesis and Reactivity of Isoxazoles: Metal Catalysis and Beyond

4-Thiazolidinones: the advances continue….

Mannich bases in medicinal chemistry and drug design.

The molecular structures and spectral properties of α-haloketones as well as their syntheses are analyzed and reviewed. Their reactivity towards oxygen, nitrogen, and sulfur nucleophiles, carboxylic acids, carbon nucleophiles, alkenes, and alkynes are discussed.

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The Chemistry of α-Haloketones and Their Utility in Heterocyclic Synthesis

Amino acids and amines have been used to catalyze three component hetero-domino Knoevenagel/Diels−Alder/epimerization reactions of readily available various precursor enones (1a−l), aldehydes (2a−p), and 1,3-indandione (3). The reaction provided excellent yields of highly substituted, symmetrical and nonsymmetrical spiro[cyclohexane-1,2‘-indan]-1‘,3‘,4-triones (5) in a highly diastereoselective fashion with low to moderate enantioselectivity. The Knoevenagel condensation of arylaldehydes (2a−p) and 1,3-indandione (3) under organocatalysis provided arylidene-1,3-indandiones (17) in very good yields. We demonstrate for the first time amino acid- and amine-catalyzed epimerization reactions of trans-spiranes (6) to cis-spiranes (5). The mechanism of conversion of trans-spiranes (6) to cis-spiranes 5 was shown to proceed through a retro-Michael/Michael reaction rather than deprotonation/reprotonation by isolation of the morpholine enamine intermediate of cis-spirane (22). Prochiral cis-spiranes (5ab) and trans...

https://www.scripps.edu/barbas/pdf/RamcharyJOC04.pdf

Direct organocatalytic asymmetric heterodomino reactions: the Knoevenagel/Diels-Alder/epimerization sequence for the highly diastereoselective synthesis of symmetrical and nonsymmetrical synthons of benzoannelated centropolyquinanes.

Reactions with 4-(Cyanoacetyl)phenazone: Synthesis of Novel Thiazole, Hydrazinopyrazole and Pyrazolo(5,1-c)(1.2.4)triazine Derivatives.

The (Z)-2-arylidene-quinuclidines 5 - 8 were synthesized. Their reaction with aliphatic dibasic functional reagents in both basic and acidic conditions afforded the fused heterocycles 9, 10 and 11. However, the reaction of arylidene derivative 5 with an aromatic dibasic functional reagent gave benzimidazole 13 in lieu of the anticipated tetracyclic system, quinuclidino[3,2-e]benzo[b]-1,4-diazepine 12. Cycloadditions of 5 with different reagents gave the heterocyclic derivatives 17, 19, 22 and 23. Acid-catalyzed cyclization of 5 with excess resorcinol gave 24. Compounds 9a, 19 and 24 showed antibacterial activities.

/pdf/synthetic-entry-to-tricyclic-and-tetracyclic-quinuclidine-3abomi7rwx.pdf

Hanafi H. Zoorob

Papers

Reactions with 4-(Cyanoacetyl)phenazone: Synthesis of Novel Thiazole, Hydrazinopyrazole and Pyrazolo(5,1-c)(1.2.4)triazine Derivatives.

Synthetic Entry to Tricyclic and Tetracyclic Quinuclidine Derivatives by Cycloaddition and Ring Transformation

Narrative in the chemistry of (aryl/hetaryl)thiopyran-4-one

Synthesis, characterization and RHF/ab initio simulations of 2-amino-1,3,4-thiadiazole and its annulated ring junction pyrimidine derivatives

Chemistry of Bicyclic Pyridines Containing a Ring-Junction Nitrogen