Zhenfeng Xi

Reaction of 3-zircona-1-cyclopentenes and zirconacyclopentanes with aldehydes. A selective and convenient synthesis of 4-penten-1-ols, (Z)-5-iodo-4-penten-1-ols, and related alkanols

Abstract 3-Zircona-1-cyclopentenes and zirconacyclopentanes react with aldehydes at or below 25 °C to give the corresponding carbonyl addition products, i.e., 7-membered oxazirconacycles, which can be readily converted to the corresponding alcohols via protonolysis and 5-iodoalcohols via iodinolysis; the latter product can be further converted to 7-membered lactones via Pd-catalyzed carbonylation.

Convenient preparative method of α,β-disubstituted cyclopentenone by zirconium promoted intermolecular coupling of an alkyne, EtMgBr (or ethylene) and CO

Abstract Treatment of Cp2ZrCl2 with 2 equiv of EtMgBr in THF, followed by addition of an internal alkyne and subsequent treatment with COI2 gave α,β-disubstituted cyclopentenone in good to high yields. When a conjugated enyne was used as an alkyne component, α-alkenyl cyclopentenone was selectively formed in 80–89% yields. In the case of 4,6-decadiyne, α-alkynylcyclopentenone was formed in 88% yield. Bridged alkynes such as 1,4-dihexynylbenzene afforded α,α′-bridged cyclopentenone compounds in good yields.

Cu(I) Catalyzed or Promoted Metallacycle Transfer of Zirconacycles to Stannacycles.

Abstract Zirconacyclopentadienes, zirconacyclopentenes and zirconacyclopentanes were readily transferred to the corresponding stannacycles in the presence of a catalytic or a stoichiometric amount of CuCl. Without CuCl, the above transfer did not proceed at all or proceeded very slowly. A convenient one-pot procedure for the preparation of spiro stannacyclopentadiene compounds was also developed with CuCl.

Selective one carbon-carbon bond formation reaction of zirconacyclopentadienes with aryl iodides or alkynyl iodides

Abstract Reaction of zirconacyclopentadienes with one equiv or two equiv of aryl iodides in the presence of CuCl and DMPU afforded mono-arylated diene derivatives in high yields with high selectivities. Treatment of zirconacyclopentadienes with one equiv of 2-thienyl iodide similarly gave thienyldienes in the presence of CuCl and DMPU, whereas the reaction with two equiv of 2-thienyl iodide produced thienyl iododiene derivatives in high yields. Zirconacyclopentadienes reacted with two equiv of alkynyl iodides to give iododienynes in good yields in the presence of CuCl. This is in sharp contrast to the reaction with two equiv of alkynyl iodides in the presence of CuCl and DMPU which provides dienediynes.

Preparation of 1,2,3-trisubstituted cyclopentadienes and tetrahydroindene derivatives from zirconacyclopentenes

Abstract 1,2,3-Trisubstituted cyclopentadienes and tetrahydroindene derivatives were prepared by a one-step reaction from zirconacyclopentene complexes, which are easily prepared from alkynes and EtMgBr (or ethylene) and Cp 2 ZrCl 2 . Reaction of zirconacyclopentenes with phthaloyl chlorides afforded intramolecular Michael addition reaction products. The structure of one of the products was determined by X-ray study.

Cycloaddition of zirconacyclopentadienes to alkynes using copper salts: formation of benzene derivatives

Reaction of zirconacyclopentadienes with alkynes such as dimethyl acetylenedicarboxylate gives benzene derivatives in the presence of CuCl/LiCl.

Generation of cyclobutadiene derivatives from 1-metallo-4-halobuta-1,3-diene derivatives

1-Zircona-4-halobuta-1,3-diene derivatives react in the presence of CuCl to produce cyclobutadiene derivatives which afford their dimers, or Diels–Alder adducts with dimethyl maleate or fumarate.

Formation of a five-membered carbocyclic ring by reaction of zirconacyclopentane with RCOCl (R = Ph, Pri, Et)

Zirconacyclopentane reacts with RCOCl in the presence of a catalytic amount of CuCl/LiCl to give a five-membered carbocyclic ring.