Gold-Catalyzed Cycloisomerization of 1,6-Diyne Carbonates and Esters to 2,4a-Dihydro-1H-fluorenes
摘要:
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.
Gold-Catalyzed Cycloisomerization of 1,6-Diyne Carbonates and Esters to 2,4a-Dihydro-1H-fluorenes
摘要:
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.
A novel K2CO3-mediated cyclization and rearrangement of γ,δ-alkynyl oximes for the synthesis of pyridols is described. The process accomplishes an efficient [1,3] rearrangement of the O-vinyl oxime intermediate which is in situ generated from the intramolecular nucleophilic addition of γ,δ-alkynyl oximes. The reaction employs readily accessible starting materials, tolerates a wide range of functional
描述了一种新颖的K 2 CO 3介导的γ,δ-炔基肟的环化和重排,用于合成吡咯。该方法完成了O-乙烯基肟中间体的有效[1,3]重排,该中间体是由γ,δ-炔基肟的分子内亲核加成反应原位产生的。该反应采用容易获得的起始原料,耐受各种官能团,并以高收率得到各种合成上具有挑战性的吡咯。