In the last decade a certain number of new cyclobutane and cyclobutanone synthesis functionalization protocols have been published. Organo- biocatalyzed eco-friendly approaches to cyclobutane-containing molecules developed with interesting results. Also, successful total bioactive compounds drugs recently reported where four membered ring represented key intermediate. Therefore, rising interest in this field represents great point discussion for scientific community, disclosing synthetic...

Regioselective synthesis of 2,4,5- or 3,4,5-trisubstituted 2,3-dihydrofurans has been realized by using donor−acceptor cyclopropanes a Corey ylide reaction with α-sulfenyl-, α-sulfinyl-, α-sulfonylenones. The method allowed straightforward the natural product calyxolane B.

An overview of the most important synthetic strategies currently available for preparation cyclopent-2-enones is presented and illustrated with recent applications. 1 Introduction 2 Multicomponent Ring Assembly 3 Cyclizations 4 Transformations Existing Cyclic Systems 5 Miscellaneous Methods 6 Conclusions

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

Abstract A catalytic enantioselective synthesis of α‐arylaminocyclobutanones from racemic α‐hydroxycyclobutanone and a selection N ‐alkylanilines has been established, via tandem condensation/keto‐enol tautomerization process reminiscent the Amadori Heyns rearrangements. magnified image

A new solvent-free Brønsted acid catalysed cascade reaction has been established, allowing access to highly substituted tryptamines under mild conditions.

A novel synthesis of optically active α-arylamino ketones through an organocatalytic enantioselective Amadori–Heyns rearrangement is described.

N-Phenylsulfonyl (S)-proline catalyzes the direct aldol reaction of 3-substituted cyclobutanones and aryl aldehydes in good yield with excellent diastereoselectivity enantioselectivity. This desymmetrization process provides highly functionalized control over three contiguous stereogenic centers.

Abstract 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 selection benzylamines. This sequence afforded the products in good to high yields with moderate enantioselectivities.

An unprecedented acid promoted structural reorganization of pull‐pull alkylidenecyclobutanes into 3‐substituted γ‐butyrolactones, in moderate to high yields, via a ring closure‐ring contraction followed by intramolecular ring‐opening cyclization is described.

A cascade reaction has been established that enables access to structurally diverse 2‐oxabicyclo[3.2.0]heptan‐3‐ones bearing a benzo[d]oxazol‐2(3H)‐one moiety at the bridgehead quaternary center in moderate good yields single operation. The illustrates potential of 2‐hydroxycyclobutanone as substrate for rapid preparation unusual and complex molecular frameworks.

[reaction: see text] Acid-catalyzed ring expansion of chiral cyclopropyl and cyclobutyl derivatives for the synthesis carbo- heterocyclic compounds is reported. The starting materials have been successfully prepared by l-proline-catalyzed direct asymmetric aldol reactions 1-phenylthiocycloalkyl carboxaldehydes with ketones.

The structure of a series I−O bonded bis(acyloxy)iodoarenes and benzoiodoxolones in chloroform solution has been investigated by 17O NMR spectroscopy density functional theory (DFT) calculations, employing the PBE0 together with LANL2DZ basis set extended polarization (d) diffuse (p) functions. This combined approach allowed us to ascertain that, although these classes λ3 iodanes maintain their solid state "T-shaped" structure, degenerate [1,3] sigmatropic shift iodine between two oxygens...

Abstract We describe a photochemical reaction using two starting materials, cyclopent‐2‐enone and an alkene, which are transformed in 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 formed through tandem triple cascade processes, respectively. Small libraries of each compound class were prepared, thus suggesting that...

Abstract 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.

A general strategy for the synthesis of indolyl cyclopropanecarbaldehydes and ketones via a Brønsted acid-catalyzed indole nucleophilic addition/ring-contraction reaction sequence has been exploited. The procedure leads to wide panel cyclopropyl carbonyl compounds in generally high yields with broad substrate scope.

Abstract The first highly enantioselective organocatalytic rearrangement of α‐acyloxy‐β‐keto sulfides to α‐acyloxy thioesters has been developed which provides a number important synthetic building blocks in high yield and with excellent enantioselectivities ( ee : up 92%).

An eco-friendly methodology for the direct α-sulfanylation of ketones has been developed by using diaryl disulfides as sulfanyl source affording ketosulfides in good to excellent yields and high selectivity.

An unprecedented and conceptually novel chiral Brønsted base/Brønsted acid catalytic method for the enantioselective synthesis of α-amino thioesters through a tandem condensation-intramolecular rearrangement-protonation has been developed which provides number important synthetic building blocks in good yield with moderate to enantioselectivities.

A general strategy for the synthesis of arylthio cyclopropyl carbaldehydes and ketones via a Brønsted acid catalyzed arylthiol addition/ring contraction reaction sequence has been exploited. The procedure led to wide panel in generally high yields with broad substrate scope. Mechanistic aspects synthetic applications this were investigated.

An original tandem reaction consisting of a Wittig reaction–ring contraction process between α-hydroxycyclobutanone and phosphonium ylides has been developed. Highly functionalized cyclopropanecarbaldehydes are obtained in good to high yield.

A continuous flow Norrish–Yang photocyclization of 1,2-diketones has been developed and applied to the synthesis functionalized 2-hydroxycyclobutanones, under blue light irradiation.

The potential of aerogels as catalysts for the synthesis a relevant class bis-heterocyclic compounds such bis(indolyl)methanes was investigated. In particular, studied catalyst nanocomposite aerogel based on nanocrystalline nickel ferrite (NiFe2O4) dispersed amorphous porous silica obtained by two-step sol–gel followed gel drying under supercritical conditions and calcination treatments. It found that NiFe2O4/SiO2 is an active selected reaction, enabling high conversions at room temperature,...

The first use of the Julia-Lythgoe-type olefination with cyclopropylsulfones and cyclopropylsulfoxides for synthesis alkylidenecyclopropanes is reported.