title: Gold-catalyzed cycloisomerization of 1,6-diyne carbonates and esters to 2,4a-dihydro-1H-fluorenes.
abstract: A synthetic method to prepare 2,4a-dihydro-1H-fluorenes efficiently from gold(I)-catalyzed 1,2-acyloxy migration/cyclopropenation/Nazarov cyclization of 1,6-diyne carbonates and esters is described. The suggested reaction pathway provides rare examples of [2,3]-sigmatropic rearrangement in this class of compounds as well as the involvement of an in situ formed cyclopropene intermediate in gold catalysis. Experimental and ONIOM(QM:QM') [our own n-layered integrated molecular orbital and molecular mechanics(quantum mechanics:quantum mechanics')] computational studies based on the proposed Au carbenoid species provide insight into this unique selectivity.
authors.affiliation: Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore.
authors.forename: Weidong
authors.initials: W
authors.lastname: Rao
authors.forename: Ming Joo
authors.initials: MJ
authors.lastname: Koh
authors.forename: Dan
authors.initials: D
authors.lastname: Li
authors.forename: Hajime
authors.initials: H
authors.lastname: Hirao
authors.forename: Philip Wai Hong
authors.initials: PW
authors.lastname: Chan