Remote Stereocontrol in the Nazarov Reaction: A New Approach to the Core of Roseophilin
摘要:
Three different procedures are compared to obtain properly substituted divinyl ketones in which one of the double bonds is embedded in a five-membered heterocyclic structure and therefore suitable to produce cyclopenta-fused pyrrole derivatives by the acid-catalyzed Nazarov reaction. These, on treatment with TFA, afforded 2,4-cis-disubstituted 2,3,4,5-tetrahydro-1H-cyclopenta[b]pyrrol-6-ones with high stereocontrol. One of these Nazarov products was oxidized to the corresponding 4,5-dihydro-1H-cyclopenta[b]pyrrol-6-one derivative, thus obtaining an enantiopure key intermediate in the total synthesis of roseophilin.
One-Pot Double-Annulation Strategy for the Synthesis of Unusual Fused Bis-Heterocycles
作者:Shukree Abdul-Rashed、Georgios Alachouzos、William W. Brennessel、Alison J. Frontier
DOI:10.1021/acs.orglett.0c01351
日期:2020.6.5
A novel metal-free double-annulation cascade for the construction of unusual fused heterocyclic systems is described. This simple protocol enables the sequential assembly of two rings in one pot from two simple precursors. Acidic conditions promote the condensation and the intramolecular alkynyl Prins reaction of an enyne or arenyne alcohol with a cyclic hemiaminal to form a five-, six-, or seven-membered
Published as part of the Special Topic Modern Cyclization Strategies in Synthesis Abstract An iridium/dppf complex efficiently catalyzed the oxidativecyclization of N-sulfonyl alkenyl amides and alkenoic acids. Electron-deficient alkenes were effective as sacrificial hydrogen acceptors. High selectivity of the oxidativecyclization over the competing addition reaction has been realized by the use
Remote Chiral Induction in Vinyl Sulfonium Salt-Mediated Ring Expansion of Hemiaminals into Epoxide-Fused Azepines
作者:Muhammad Yar、Matthew G. Unthank、Eoghan M. McGarrigle、Varinder K. Aggarwal
DOI:10.1002/asia.201000817
日期:2011.2.1
The planet of the azepines: Epoxy‐fused azepines have been synthesized in a highly selective reaction with hemiaminals and vinyl sulfonium salts. Stereochemistry is controlled by the substituent at the four‐ or five‐position of the hemiaminal. The key step involves ring‐opening of the hemiaminal, conjugate addition onto a vinyl sulfonium salt, and epoxidation of the aldehyde by the in situ formed sulfur
Carbonylative Suzuki–Miyaura Coupling Reaction of Lactam-, Lactone-, and Thiolactone-Derived Enol Triflates for the Synthesis of Unsymmetrical Dienones
作者:Laura Bartali、Antonio Guarna、Paolo Larini、Ernesto G. Occhiato
DOI:10.1002/ejoc.200601089
日期:2007.5
carbonylative Suzuki–Miyaura cross-coupling reaction of enoltriflates with alkenylboronic acids for the synthesis of unsymmetrical dienones is reported. Conditions were found that enabled the coupling of structurally different enoltriflates derived from lactams, lactones, and thiolactones (i.e., cyclic ketene aminal, acetal, and thioacetal triflates, respectively) with various alkenylboronic acids at
Cobalt-Catalyzed Cyclization of Unsaturated <i>N</i>-Acyl Sulfonamides: a Diverted Mukaiyama Hydration Reaction
作者:David M. Fischer、Moritz Balkenhohl、Erick M. Carreira
DOI:10.1021/jacsau.2c00186
日期:2022.5.23
The cycloisomerization of β-, γ-, and δ-unsaturated N-acyl sulfonamides to N-sulfonyl lactams and imidates is reported. This transformation is effected in the presence of a CoIII(salen) catalyst using t-BuOOH or air as the oxidant. The method shows good functional group tolerance (alkyl, aryl, heteroaryl, ether, N-Boc) and furnishes an underexplored class of cyclic building blocks. The strong solvent
报道了β-、γ-和δ-不饱和N-酰基磺酰胺环异构化为N-磺酰基内酰胺和亚胺酸酯。这种转变是在 Co III (salen) 催化剂的存在下使用t -BuOOH 或空气作为氧化剂进行的。该方法显示出良好的官能团耐受性(烷基、芳基、杂芳基、醚、N -Boc),并提供了一类尚未开发的环状结构单元。研究了转化的强溶剂依赖性,并强调了N-磺酰亚胺酯产品类的合成多功能性。