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...

Regioand stereoselective reductions of several diketones to afford enantiopure hydroxy ketones or diols were accomplished using isolated alcohol dehydrogenases (ADHs). Results could be rationalised taking into account different (promiscuous) substrate-binding modes in the active site of the enzyme. Furthermore, interesting natural cyclic diketones were also reduced with high regioand stereosele...

The synthesis of Pd nanoparticles (Pd-NPs) supported on multiwalled carbon nanotubes (MWCNTs) and the cataytic performance of the resulting material (PdNPs/MWCNTs) on hydrogenation reactions are presented. Facile preparation approaches based on the decomposition of Pd precursors in the presence of MWCNTs lead to homogeneous dispersions of supported Pd-NPs with average size of 4 nm and Pd loads ...

Volatile compounds in honey samples of different botanical origins were investigated. Solid phase microextraction (SPME) and gas chromatography-mass spectrometry (GC/MS) revealed a total of 86 compounds in the headspace of 4 types of honey – multifloral, heather, buckwheat and lime-honeydew. The chemical composition of the headspace was very diverse, owing to the presence of compounds from diff...

The formation of an unexpected heterocyclic scaffold, a benzoxazole, in a three-component reaction between a ketone, isocyanide, and 2-aminophenol was encountered. This reaction involved a benzo[b][1,4]oxazine intermediate resulting from intramolecular attack of the aminophenol hydroxyl group on the nitrilium ion. Unlike previous literature examples, the trapped nitrilium benzo[b][1,4]oxazine c...

Porcine pancreas lipase type II (PPL II) exhibited unnatural catalytic activity in direct asymmetric aldol reactions between cyclic ketones and aromatic or heteroaromatic aldehydes in acetonitrile in the presence of phosphate buffer. A wide range of substrates was accepted by the enzyme to afford the corresponding aldol products in low to high yields (10-98%), with moderate to excellent enantio...

A synthesis of 1,1-disubstituted 1,2,3,4-tetrahydroisoquinolines (6) was achieved in a highly efficient manner via Pictet-Spengler reaction of arylethylamines (1) and acyclic and cyclic ketones (2) using titanium (IV) isopropoxide and acetic-formic anhydride. The cyclization of the in situ formed acyliminium ion (4) to N-formyl 1,2,3,4-tetrahydroisoquinoline (5) was greatly facilitated by using...

We report a peptide-based catalyst that can strongly influence the regio- and enantioselectivity of the Baeyer-Villiger (BV) oxidation of cyclic ketones bearing amide, urea, or sulfonamide functional groups. Both types of selectivity are thought to arise from a catalyst-substrate hydrogen-bonding interaction. Furthermore, in selected cases, the reactions exhibit the hallmarks of parallel kineti...

Dienes embedded in quinolizidine and indolizidine structures can be prepared in four steps from cyclic nitrones and bicyclopropylidene. The key intermediates α-spirocyclopropanated N-heterocyclic ketones, generated via a domino 1,3-dipolar cycloaddition/thermal rearrangement sequence, were converted by Wittig methylenation to the corresponding vinylcyclopropanes (VCPs), which underwent rearrang...

Novel 5α-androstanes containing an isoxazoline moiety condensed to ring A or D were efficiently synthetized by 1,3-dipolar cycloadditions of aryl nitrile oxides to steroidal α,β-unsaturated ketones. During the ring closures, regioisomers in which the O terminus of the nitrile oxide dipoles is attached to the β-carbon of the dipolarophile were formed in a stereoselective manner to furnish exclus...