Gold(I)-Catalyzed Inter- and Intramolecular Additions of Carbonyl Compounds to Allenenes.

The gold(I)-catalyzed intramolecular reaction of allenes with oxoalkenes leads to bicyclo[6.3.0]undecane ring systems, although in the case of terminally disubstituted allenes, seven-membered rings are formed. The related intermolecular addition of aldehydes to allenenes also gives seven-membered rings.

Access to the protoilludane core by gold-catalyzed allene-vinylcyclopropane cycloisomerization.

Gold(I)-catalyzed allene-vinylcyclopropane cycloisomerization leads to the tricyclic framework of the protoilludanes in a single step by a reaction that involves a cyclopropane ring expansion and a Prins cyclization.

Asymmetric synthesis of (+)-castanospermine through enol ether metathesis-hydroboration/oxidation.

An asymmetric synthesis of (+)-castanospermine is presented in which enol ether metathesis-hydroboration/oxidation is used for stereoselective installation of the trans-trans hydroxyl groups on the piperidine ring of the alkaloid.

Toward the total synthesis of spirastrellolide A. Part 3: intelligence gathering and preparation of a ring-expanded analogue.

Different methods for the formation of the C.25-C.26 bond of spirastrellolide A () are evaluated that might qualify for the end game of the projected total synthesis, with emphasis on metathetic ways to forge the macrocyclic frame.

Asymmetric [2 + 2] cycloaddition: total synthesis of (-)-swainsonine and (+)-6-epicastanospermine.

[reaction: see text] An asymmetric total synthesis of (-)-swainsonine and (+)-6-epicastanospermine is described from a common intermediate, which is obtained through diastereoselective [2 + 2] cycloaddition of dichloroketene to a chiral enol ether.