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This concept review describes the recent achievements on the Heyns rearrangement appeared in literature over the last decade and aims to provide the reader with a general overview of the fundamental synthetic advances in this research area. [ABSTRACT FROM AUTHOR]

A stereoselective one‐pot double derivatization of cyclobutene‐1‐carboxylic acid via a mild organic base catalyzed amidation/aza‐Michael addition of benzo[d]oxazol‐2(3H)‐ones has been developed. This unprecedented tandem reaction provides access to novel β‐N‐heterocyclic cyclobutane carboximide derivatives with a trans geometry. The carboximide moiety reacts smoothly with nucleophiles, allowing access to diverse derivatives of trans‐β‐N‐heterocyclic cyclobutanecarboxylic acid, including peptidomimetic structures. [ABSTRACT FROM AUTHOR]

A solvent‐free organocatalyzed intermolecular cyclization reaction starting from β‐substituted γ‐hydroxy‐α,β‐unsaturated esters and aryl isothiocyanates proceeds via an aza‐Michael addition to provide previously unknown quaternary oxazolidine‐2‐thione β3‐amino ester analogs. A panel of diversely‐substituted esters was investigated, including β,γ‐disubstituted examples which provided the target molecules with very high cis diastereoselectivity. [ABSTRACT FROM AUTHOR]

A synthetically useful Z‐selective cascade formal thiyl radical addition, 1,3‐double bond isomerization, oxygen trapping reaction, can be promoted by Eosin B under visible light, leading to the construction of 2‐aryl‐ and alkylthio enone derivatives in good yields. An accurate study on the reactivity of different thiols and the screening of the reaction conditions, allowed us to extend this reaction to a large number of substrates, showing a good functional groups tolerance while highlighting the limitations of this procedure. Background experiments and mechanistic studies were also. performed to rationalize this cascade process. The usefulness of this methodology was finally demonstrated via the transformation of a series of α‐sulfanyl‐enone adducts through selected oxidation reactions, stereoselective synthesis of cyclopropyl ketones, indanones, and pyrazole compounds. [ABSTRACT FROM AUTHOR]

We have developed one‐step protocols for the preparation of a large selection of α‐aminocyclopropyl ketones or benzo[d]imidazoles, by reacting 2‐substituted‐2‐hydroxycyclobutanones with aryl amines or o‐phenylenediamines, respectively. In most case the reactions proceed at room temperature and are catalyst‐free. The formation of benzo[d]imidazoles is rationalized in terms of an unusual ring‐closure/ring‐fission process followed by aromatization. [ABSTRACT FROM AUTHOR]

A new Brønsted acid catalysed solvent‐free cascade reaction consisting of a ring closure‐ring fission process between α‐arylaminocyclobutanones and alcohols has been established, providing highly functionalised 3‐(2‐alkoxyethyl)indoles in good to excellent yields. [ABSTRACT FROM AUTHOR]

Abstract: We describe a photochemical reaction using two starting materials, a cyclopent‐2‐enone and an alkene, which are transformed in a controlled manner via the initial [2+2]‐photocycloaddition adducts into cyclobutene aldehydes (conveniently trapped as stable acetals) or unprecedented angular tricyclic 4:4:4 oxetane‐containing skeletons. These compounds are formed through tandem or triple cascade photochemical reaction processes, respectively. Small libraries of each compound class were prepared, thus suggesting that this photochemistry approach opens new opportunities for synthesis design and for widening molecular diversity. [ABSTRACT FROM AUTHOR]

The Paternò-Büchi reaction between benzaldehyde and trimethylsilyloxycyclopentene gave access to an unprecedented silyl ether derivative of 6-oxabicyclo[3.2.0]heptan-1-ol. The bicyclic structure underwent selective reductive ring opening and acid-catalyzed pinacol-type rearrangement reactions with complete regioselectivity, accompanied by moderate to excellent mechanism-dependent diastereoselectivity. [ABSTRACT FROM AUTHOR]

An organocatalytic enantioselective synthesis of α-(benzylamino)cyclobutanones has been achieved by employing a tandem condensation/intramolecular rearrangement/proton transfer reaction and starting from racemic α-hydroxycyclobutanone and a selection of benzylamines. This reaction sequence afforded the products in good to high yields with moderate to high enantioselectivities. [ABSTRACT FROM AUTHOR]

A variety of enantiomerically enriched tetrahydrofuran spirocyclic derivatives have been synthesised by a sequential enantioselective proline-induced stereospecific resolution through aldol reaction of ( E/ Z)-(phenylsulfanyl)cycloalkanecarbaldehydes followed by a ketone reduction, acid-catalysed [1,2]-SPh stereospecific migration, and ring-closure reaction. [ABSTRACT FROM AUTHOR]

BACKGROUND The gypsy moth Lymantria dispar L. is a widespread pest that causes economic damage to cork oak forests. Females produce the sex pheromone (+)-(7 R,8 S)-epoxy-2-methyloctadecane, known as (+)-disparlure [(+)D], for long-distance attraction of conspecific males. A (+)D analogue, 2-decyl-1-oxaspiro[2.2]pentane ( OXP-01), neither stimulating nor attractive by itself, causes short-time inhibition of male response in a 1:1 blend with (+)D. The authors investigated whether and how the biological activity of the natural pheromone is affected by OXP-01 on a long-time basis (up to 16 days), also by looking at possible physicochemical reciprocal interactions. RESULTS Blending of (+)D with OXP-01 decreased, under low evaporation rate, the pheromone effectiveness, as assessed by electroantennogram recordings. In male trappings, within the first 24 h, OXP-01 decreased and later enhanced the blend attractiveness, but only under high evaporation rate. Gas chromatography-mass spectroscopy indicates that quantitative retrieval of (+)D from blend cartridges is higher than for pure pheromone, and nuclear magnetic resonance measurements show that OXP-01 produces, possibly by Van der Waals interactions, a bimolecular entity with pheromone causing retention and lengthening of its attractiveness over time. CONCLUSION The biological and physicochemical interactions between (+)D and OXP-01 may provide valuable information for the optimisation of pheromone-based control strategies for gypsy moths. © 2013 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

A practical method for the synthesis of optically active α-amino cyclobutanones has been developed, via an organocatalytic asymmetric condensation reaction between racemic 2-hydroxycyclobutanone and chiral N-alkyl-α-amino acid ester derivatives. [ABSTRACT FROM AUTHOR]

A catalytic enantioselective synthesis of α-arylaminocyclobutanones from racemic α-hydroxycyclobutanone and a selection of N-alkylanilines has been established, via a tandem condensation/keto-enol tautomerization process reminiscent of the Amadori and Heyns rearrangements. [ABSTRACT FROM AUTHOR]

A novel metal-free proline-catalyzed protocol is presented for the sulfanylation of cyclic and acyclic ketones by using diphenylsulfides. [ABSTRACT FROM AUTHOR]

The reaction provides 3-alkyl/aryl-2-(2-nitro-1-alkyl/aryl)cyclo-1-butanones as mixture of the two diastereomers bearing a trans-ring configuration. [ABSTRACT FROM AUTHOR]

Review: 127 refs. [ABSTRACT FROM AUTHOR]

L-proline-catalyzed aldol reaction can be used for the resolution of diastereomers (I) and (VII) yielding the aldol products with high enantioselectivity. [ABSTRACT FROM AUTHOR]

Review: 127 refs. [ABSTRACT FROM AUTHOR]

The catalyst can be recycled and reused without loss of the catalytic activity. [ABSTRACT FROM AUTHOR]

Title compounds [(III), (V), and (VIII)] are synthesized in good yields and good enantioselectivities. [ABSTRACT FROM AUTHOR]