The [3,5,5,7] tetracyclic skeleton of echinopines has been stereoselectively accessed through a gold(I)-catalyzed alkoxycyclization of cyclopropyl-tethered 1,6-enynes. The key bicyclo[4.2.1]nonane core of the enyne precursors was readily assembled by means of a Co-catalyzed [6 + 2] cycloaddition. Furthermore, the attempted alkoxycyclization of 1,5-enyne substrates revealed an uncovered cyclopro...

The title compound, C(22)H(28)O(4), is composed of a central octa-decane ring and two spiro-[bicyclo-[2.2.1]hept[2]ene-7,2'-[1,3]dioxolane] units. This polycycle has pseudo twofold symmetry and the central cyclo-octane ring has a distorted boat configuration.

The synthesis of the lipophilic chiral amino acid 1 bearing the bicyclo[1.1.1]pentane moiety is described. Linear and cyclic hexapeptides of the type Arg-Arg-Xaa-Yaa-Arg-Phe containing 1 instead of one or two tryptophan residues are prepared by solid phase peptide synthesis and the antimicrobial and hemolytic activity of the peptides obtained are discussed.

Cross-conjugated trienamines are introduced as a new concept in asymmetric organocatalysis. These intermediates are applied in highly enantioselective Diels-Alder and addition reactions, providing functionalized bicyclo[2.2.2]octane compounds and γ'-addition products, respectively. The nature of the transformations and the intermediates involved are investigated by computational calculations an...

Access to the bicyclo[5.3.0]decane core found in the daucane and sphenolobane terpenoids via a key enone intermediate enables the enantioselective total syntheses of daucene, daucenal, epoxydaucenal B, and 14-para-anisoyloxydauc-4,8-diene. Central aspects include a catalytic asymmetric alkylation followed by a ring contraction and ring-closing metathesis to generate the five- and seven-membered...

The Lewis acid catalyzed cyclization of hexatrienes and pentadienals to bicyclo[3.1.0]hexenes and cyclopentenones, respectively, was investigated. The application of the former reaction to the total synthesis of photodeoxytridachione, a molluscan polypropionate, is described. q 2003 Elsevier Ltd. All rights reserved.

The commercially available monoterpene carvone has been efficiently converted into the tricyclo[3.2.1.0(2.7)]octane and bicyclo[3.2.1]octane systems characteristic of some biologically active compounds. The sequence used for this transformation involves as key features an intramolecular Diels-Alder reaction of a 5-vinyl-1,3-cyclohexadiene and a cyclopropane ring opening.

The maturation of Madeira wines usually involves exposure to relatively high temperatures which affect the aroma and flavour composition leading to the formation of the typical and characteristic bouquet of these wines. The formation of heterocyclic acetals (1,3-dioxanes and 1,3-dioxolanes) was investigated in order to determine levels and for possible use as indicators of wine age. The results...

Ternary Ni(II) complexes of hydrazine and eight heterocyclic sulfonamides possessing carbonic anhydrase (CA) inhibitory properties, were prepared and characterized by elemental analysis, spectroscopic, magnetic, thermogravimetric, and conductimetric measurements. The complexes behave as strong inhibitors for two isozymes (I and II) of carbonic anhydrase.