Indium(III) triflate catalysed transacetalisation reactions of diols and triols under solvent-free conditions

A General Metal-Free Protocol for the Visible-Light-Driven Protection of Carbonyls

The protection of a carbonyl is a standard procedure to mask the reactivity of this group towards nucleophiles and reductants. The present work pointed out the potentialities of arylazo sulfones as non-ionic photoacid generators (PAGs) to promote the efficient conversion of aldehydes and ketones into acetals, ketals, and 1,3-oxazolidines upon visible-light irradiation. This approach employed mild conditions and exhibited an easy scalability and a broad scope (80 examples included).

Nickel-Catalyzed Chemoselective Acetalization of Aldehydes With Alcohols under Neutral Conditions

A molecularly defined Ni^II -complex catalyzing the chemoselective acetalization of aldehydes with alcohols under neutral conditions is reported. The reaction is general, efficient and showed a wide substrate scope (including aliphatic aldehydes) as well as excellent functional group tolerance. Reusability of the present nickel catalyst is also demonstrated.

Metal Triflate-Promoted Allylic Substitution Reactions of Cinnamyl Alcohol in the Presence of Orthoesters and Acetals

The product distribution of ethers formed from the reaction of cinnamyl alcohol with orthoesters in the presence of indium (III) triflate (InOTf)3 is dependent on both the reaction temperature and catalyst loading. Carrying out the reaction at room temperature under low loadings of the catalyst leads to a facile reaction generating the unexpected secondary allyl ether as the major product. In contrast, carrying out the reaction under higher catalyst loadings at elevated temperatures provides the expected primary linear ether in high yield and with excellent selectivity. The etherification reaction is also effective in the presence of acetals and ketals in place of orthoesters and allows for the development of the procedure to encompass a telescoped etherification protocol in which the acetal is generated in situ.

Controlled cationic copolymerization of vinyl monomers and cyclic acetals via concurrent vinyl-addition and ring-opening mechanisms: the systematic study of structural effects on the copolymerization behavior

The effects of the structures of cyclic acetals on the copolymerization behavior were systematically investigated in the cationic copolymerization with vinyl ethers.

A Simple and Versatile Method for the Formation of Acetals/Ketals Using Trace Conventional Acids

An important and surprising finding that the acetalization and ketalization of aldehydes and ketones with alcohols, respectively, proceed smoothly in the presence of 0.1 mol % acid, without removing water, has been presented. This process has many merits, such as commercial available catalysts with low cost and low loadings (as low as 0.03 mol %), quite a broad substrate scope (including various aldehydes, ketones, acid-sensitive substrates, and diols), a wide range of reaction temperature (-60 to 50 °C), high yields, large-scale preparation, environmental friendliness, and simple work-up procedure. This new protocol has also been successfully applied to protect the important organic compounds, such as 1,3-diols, 1,2-diols, acid-sensitive substrates, glucose, and 1,3-dicarbonyl compounds.

Diastereoselective Flexible Synthesis of Carbocyclic C-Nucleosides

Carbocyclic C-nucleosides are quite rare. Our route enables flexible preparation of three classes of these nucleoside analogs from common precursors-properly substituted cyclopentanones, which can be prepared racemic (in six steps) or optically pure (in ten steps) from inexpensive norbornadiene. The methodology allows flexible manipulation of individual positions around the cyclopentane ring, namely highly diastereoselective installation of carbo- and heterocyclic substituents at position 1', orthogonal functionalization of position 5', and efficient inversion of stereochemistry at position 2'. Newly prepared carbocyclic C-analog of tubercidine, profiled in MCF7 (breast cancer) and HFF1 (human foreskin fibroblasts) cell cultures, is less potent than tubercidine itself, but more selectively toxic toward the tumorigenic cells.

Visible-Light-Induced Acetalization of Aldehydes with Alcohols

In this work, we have achieved a simple and general method for acetalization of aldehydes by means of a photochemical reaction under low-energy visible light irradiation. A broad range of aromatic, heteroaromatic, and aliphatic aldehydes have been protected under neutral conditions in good to excellent yields using a catalytic amount of Eosin Y as the photocatalyst. Our visible light mediated acetalization strategies are successful for more challenging acid-sensitive aldehydes and sterically hindered aldehydes. Notably, this protocol is chemoselective to aldehydes, while ketones remain intact.

nor-Mevaldic acid surrogates as selective antifungal agent leads against Botrytis cinerea. Enantioselective preparation of 4-hydroxy-6-(1-phenylethoxy)tetrahydro-2H-pyran-2-one

Solvent-free desymmetrisation of meso-dialdehyde 1 with chiral 1-phenylethan-1-ol, led to preparation of 4-silyloxy-6-alkyloxytetrahydro-2H-pyran-2-one (+)-3a with a 96:4 dr Deprotected lactone (+)-19a and the related racemic lactones 16a-18a present a lactone moiety resembling the natural substrate of HMG-CoA reductase and their antifungal properties have been evaluated against the phytopathogenic fungi Botrytis cinerea and Colletotrichum gloeosporioides. These compounds were selectively active against B. cinerea, while inactive against C. gloeosporioides.