x_~xxxx_ A total synthesis of B-cuparenone, which highlights the advantages and disadvantages of the three-carbon annulation process, is described. The cyclopentane ring system is found in numerous naturally occurring products, including such diverse compounds as steroids, prostaglandins, and terpenes. We have recently published a new method for the formation of cyclopentanones from olefins, a ...

The scope of Rh-catalyzed C–C bond cleavage/annulation biphenylene with various aromatic nitriles was studied. subsequent Rh- and Ir-catalyzed C–H activation/annulation sequence the formed 9-arylphenanthridines alkynes gave rise to cationic [4], [5], [6] helical quinolizinium salts. reaction respect structural features starting Their arrangement confirmed through single-crystal X-ray analyses s...

Spirocyclic carbazole- and acridine-lactams were prepared by Fischer-indole or Friedländer-quinoline synthesis starting from spirocyclic ketones with a lactam ring. All annulation products were obtained as mixtures of separable regioisomers, which differ only in the position of one methyl group. The starting materials were prepared from 2-pyrrolidone and 2-piperidone by a sequence of protection...

Efficient methods for the convergent synthesis of (poly)cyclic scaffolds are urgently needed in synthetic and medicinal chemistry. Herein, we describe new annulation reactions of thioalkynes with phthalimide-substituted donor-acceptor cyclopropanes, which gave access to highly substituted cyclopentenes and polycyclic ring systems. With silyl-thioalkynes, the Lewis acid catalyzed [3+2] annulatio...

Direct 2(5H)-furanone annulation produces promising cross-coupling partners incorporating mor p-bromoand p-tosyloxyphenyl groups into the 5-position of a notable 2(5H)furanone pharmacore. The present one-pot annulation method involves two distinctive reactions: (i) a powerful and crossed Ti-direct aldol addition and (ii) an acid-induced characteristic cyclocondensation, leading to 2(5H)-furanon...

Abstract Selective syntheses of coumarin and benzofuran derivatives were achieved via HClO4-mediated intermolecular annulation using phenols α-methoxy-β-ketoesters. Coumarins are formed under dehydrated conditions, whereas benzofurans in the presence water. In synthetic process benzofurans, α-methoxy-β-ketoesters converted into α-methoxyacetophenones, methoxy group is an important element annul...

A one-step preparation of xanthones via Pd-catalyzed annulation of 1,2-dibromoarenes and salicylaldehydes was developed.

Controlled isomerization of the double bond of certain Diels-Alder reactions provides substrates that, upon oxidation, give rise to products whose gross structure corresponds to that of a Robinson annulation. In these cases, the stereochemistry of the Robinson annulation product reflects the fact that the initial combination occurred in a Diels-Alder mode. Using these principles, we have synthe...

The preparation and synthetic uses of a number of bifunctional reagents (5-chloro-2-trimethylstannyl-2-pentene and related substances, (~)-1-bromo-4-methyl-3-trimethylstannyl-2-pentene, and alkyl (z)and (~)-2,3-bis(trimethylstannyl)-2-alkenoates) are described. In this work a number of useful annulation methods were developed and these annulation sequences played key roles in effecting total sy...

An efficient organocatalytic Michael-aldol cascade reaction for the asymmetric synthesis of spirocyclic oxindole derivatives fused with tetrahydrothiophenes has been developed through a formal [3+2] annulation strategy.