Pd-H from Pd/C and Triethylamine: Implications in Palladium Catalysed Reactions Involving Amines

International audienceThe palladium hydride-iminium complex generated from Pd/C and triethylamine catalyses the isomerisation of allylic alcohols into carbonyl compounds, and Pd/C catalyses the conjugate reduction of activated double bonds using triethylamine as the source of the two newly incorporated hydrogen atoms via the same complex

Diazo Transfer Reactions to 1,3-Dicarbonyl Compounds with Tosyl azide

International audienceA practical protocol for the large-scale preparation of 2-diazo-1,3-dicarbonyl compounds is described by diazo-transfer reactions with tosyl azide followed by efficient chromatographic purifications on silica gel and/or alumina

1,3-Dicarbonyl compounds in stereoselective domino and multicomponent reactions

International audienceModern organic synthesis focuses on the discovery and the development of stereoselective multiple bond-forming transformations allowing the creation of several covalent bonds in a single operation. Hence, the number of steps required to obtain a target molecule is reduced, which nicely answers to the efficiency and economy criteria of "green chemistry". In this context, 1,3-dicarbonyl compounds are exceptional synthetic platforms due to the presence of four contiguous reaction sites. This functional group density allows cascades of elemental steps from simple substrates leading to the selective formation of elaborated molecular architectures. displaying a large functional diversity

Reluctant Cross-Metathesis Reactions: The Highly Beneficial Effect of Microwave Irradiation

carbene complexes ; catalysis ; cross coupling ; metathesis ; olefinationInternational audienceThe beneficial effect of microwave irradiation versus classical thermal conditions is demonstrated through a series of comparative cross-metathesis reactions

Asymmetric organocascades involving the formation of two C-heteroatom bonds from two distinct heteroatoms

International audienceIn the vast and expanding world of enantioselective organocascades, the ones in which two C-heteroatom bonds are created from two distinct heteroatoms are rare. These fascinating domino processes constitutes real synthetic challenges and allow very convenient syntheses of diverse optically active heterocycles and also highly functionalised acyclic derivatives

Enantioselective Organocatalytic Four-Atom Ring Expansion of Cyclobutanones: Synthesis of Benzazocinones

International audienceAn enantioselective Michael addition-four-atom ring expansion cascade reaction involving cyclobutanones activated by a N-aryl secondary amide group and ortho-amino nitrostyrenes has been developed for the preparation of functionalized eight-membered benzolactams using bifunc-tional aminocatalysts. Taking advantage of the secondary amide activating group, the eight-membered cyclic products could be further rearranged into their six-membered isomers having a glutarimide core under base catalysis conditions without erosion of optical purity, featuring an overall ring expansion-ring contraction strategy

Michael Addition-Initiated Sequential Reactions from 1,3-Dicarbonyls for the Synthesis of Polycyclic Heterocycles

International audienceThis review aims to highlight the most significant recent developments on synthetic strategies involving consecutive, domino and multicomponent reactions featuring a Michael addition-initiating step for the synthesis of polycyclic heterocycles from 1,3-dicarbonyls. These original sequences constitute more efficient and eco-compatible alternatives to known synthetic approaches to heterocyclic compounds allowing for an even faster and highly desirable generation of molecular diversity and complexity

Spirobicyclic and Tetracyclic Pyrazolidinones: Syntheses and Properties

International audienceThe stereoselective syntheses of spirobicyclic and tetracyclic pyrazolidinones are reported based on a (3+2) annu- lation between hydrazones and α-oxoketenes. Some of these conformationally constrained molecules were resolved as enantiopure materials by HPLC techniques and evaluated as amino- catalysts for iminium activation in a model Diels–Alder cyclo- addition

An Organocatalytic Two-atom Ring Expansion Approach to Optically Active Glutarimides

International audienceAn original two-step organocatalytic syn- thesis of optically active glutarimides from 2- oxocyclobutane carboxamides is described featuring an isothiourea-catalyzed two-atom ring-expansive rearrangement

Consecutive reactions with sulfoximines: a direct access to 2-sulfonimidoylylidene tetrahydrofurans and 6-sulfonimidoylmethyl- 3,4-dihydro-2H-pyrans

International audience2-Sulfonimidoylylidene tetrahydrofurans and 2-sulfonimidoylylidene-5-vinyl tetrahydrofurans were readily synthesized via a consecutive acylation/SN2 sequence with total regio- and chemoselectivity from Johnson's sulfoximine derivatives. The same consecutive reaction could also be applied to the expeditious synthesis of 6-sulfonimidoylmethyl-3,4-dihydro-2H-pyrans