Diaryl α-diketones do not undergo polarity reversal in the presence of (benzo)thiazolium carbenes but are engaged in a novel multicomponent reaction with water to efficiently give medicinally relevant 1,4-thiazin-3-one heterocycles. Three different sets of conditions have been optimized to furnish the title compounds in fair to excellent yields depending on the electronic properties of α-diketo...

The 1,6-conjugate addition of nucleophiles to dienyl diketones produces either cyclopentenone or 2H-pyran products with high selectivity through either Nazarov (4π) or 6π electrocyclization, respectively. The outcome of the reaction is dependent upon the nature of the nucleophile used. Nucleophiles that are anionic or easily deprotonated exclusively produce cyclopentenones via Nazarov cyclizati...

A one-pot, asymmetric multicatalytic formal [3+2] reaction between 1,3-dicarbonyls and alpha,beta-unsaturated aldehydes is described. The multicatalytic process involves a secondary amine catalyzed Michael addition followed by a N-heterocyclic carbene catalyzed intramolecular crossed benzoin reaction to afford densely functionalized cyclopentanones with high enantioselectivities. The reaction p...

Difluoromethanesulfonyl hypervalent iodonium ylides 2 were developed as electrophilic difluoromethylthiolation reagents for a wide range of nucleophiles. Enamines, indoles, β-keto esters, silyl enol ethers and pyrroles were effectively reacted with 2 affording desired difluoromethylthio (SCF2H)-substituted compounds in good to high yields under copper catalysis. The reaction of allyl alcohols w...

The spectra ofthe diketone compounds biacetyl, acetylacetone, acetonylacetone, 1,2cyclohexanedione, and 1,4-cyclohexanedione have been investigated by the technique oflowenergy variable-angle electron energy-loss spectroscopy. With this method low-lying, spinforbidden transitions have been observed. The energy difference between the lowest spin-allowed and spin-forbidden n-+ 1r* excitations in ...

Acylation reaction of a variety of cyclic ketones via acylation of the corresponding enamines is welldefined in the literature. Enamine acylation of carbonyl compounds is a significant synthetic method because of its mildness and the ease of preparing various β-diketones [1-4]. Acylation reactions are performed by means of converting enamines to the enaminoketones and subsequent hydrolysis of t...

Benzylidene acetone reacts with thiocyanates derived from secondary amines in a one-pot reaction to give 4-aminobicyclo[2.2.2]octan-2-ones. The reaction mixture was investigated for the presence of possible intermediates using GC-MS. These intermediates - diketones and enamines - were prepared and exposed to the same reaction conditions to examine the reaction mechanism. The reaction of ethyl s...

In this context, (Caffeine)(tetrahydroborato)zinc complex as white stable reducing agents [Zn(BH 4 ) 2 (caf)], has been prepared by complexation of one equimolar amounts of zinc tetrahydroborate and one equimolar amounts of caffeine at room temperature. Also, [Zn(BH 4 ) 2 (caf) ]has been used for reduce of a variety of carbonyl compounds such as aldehydes, ketones, α, βunsaturated carbonyl comp...