Unsaturated spirocyclic substrates bearing two alkenyl chains underwent ruthenium-mediated ring-rearrangement metathesis through relaying cyclohexene and cycloheptene moieties to give angularly fused tricyclics. In some instances where two products were expected, high degrees of selectivity were observed. In one instance the structural parameter leading to selectivity was very subtle; in others...

THE TITLE COMPOUND [SYSTEMATIC NAME: (2S*,3S*,4R*,5R*,9S*,11S*,15R*)-5,15-diacet-oxy-3-nicotino-yloxy-14-oxolathyra-6(17),12(E)-diene], C(30)H(37)NO(7), was isolated from the seeds of Euphorbia lathyris. The tricyclic diterpenoid molecule contains an 11-membered ring, a five-membered ring exhibiting an envelope conformation and a three-membered ring. The 11-membered ring is cis-fused with the t...

A series of pentacyclic heterocyclic systems (15 examples, 69-89%) have been synthesized using intramolecular Povarov reactions involving 3-aminocoumarins and O-cinnamylsalicylaldehydes. The Povarov adducts are formed with high selectivity for the trans,trans relative stereochemistry in the newly-formed [6,6] fused ring system. One example of a Povarov adduct featuring a new [6,5] fused ring sy...

Following on from our recent enforced geometry optimization (EGO) investigation of isomerization in cis-stilbene (J Comput Chem, in press) we report the discovery of two interesting new, symmetrical "fused sandwich" isomers of both cis-stilbene and the related cis-azobenzene. The isomers were obtained by applying external forces to pairs of carbon atoms from each of the benzene rings in cis-sti...

Highly stereoselective alkylative and arylative cyclization reactions of allenyl-aldehydes and -ketones with organozinc reagents occur efficiently in the presence of catalytic Ni(COD)2 to afford cis-fused homoallylic cyclopentanols.

Tandem reactions of cis-2-acyl-1-alkynyl-1-aryl cyclopropanes tuned by gold(i) and silver(i) catalysts are described, which afford selectively the key pyran-fused indene cores and the 2,4,6-trisubstituted phenols in good yields, respectively.

In the title compound (5S,8R,9R,10R,13S,14S,17R,20R)-24-bromo-5β-cholane, C(24)H(41)Br, the fused-chair conformation of the cyclo-hexane A/B ring junction is cis with a 5β-H configuration.

We present an extension of the two-point optical microrheology technique introduced by Crocker et al. [J. C. Crocker, M. T. Valentine, E. R. Weeks, T. Gisler, P. D. Kaplan, A. G. Yodh and D. A.Weitz, Phys. Rev. Lett., 2000, 85, 888] to high frequencies. The correlated fluctuations of two probe spheres held by a pair of optical tweezers within a viscoelastic medium are determined using optical i...

Herein we describe a scalable approach to the decalin moiety of maklamicin. Key to the synthesis is an intramolecular Diels-Alder (IMDA) reaction that proceeds via an endo-axial transition state to generate the desired stereochemistry. We explored the diastereoselectivity of the IMDA reaction as a function of both chiral catalysis and acyclic precursor stereochemistry.