Intermolecular [3 + 3]-Cycloadditions of Azides with the Nazarov Intermediate
摘要:
Tetrasubstituted 1,4-dien-3-ones undergo Nazarov cyclization at low temperature, followed by reaction with organic azides via an apparent [3 + 3]-cycloaddition to give bridged bicyclic triazenes. These products do not appear to be intermediates in the previously described Schmidt-type process to furnish dihydropyridones. The reaction typically occurs with high diastereoselectivity.
Olefination of α,α′-Divinyl Ketones through Catalytic Meyer−Schuster Rearrangement
作者:Curtis J. Rieder、Karl J. Winberg、F. G. West
DOI:10.1021/jo101497f
日期:2011.1.7
followed by catalytic Meyer−Schuster rearrangement has been developed for the olefination of 1,4-pentadien-3-ones to afford [3]dendralenes. Many of the traditional methods for the Meyer−Schuster rearrangement of alkynyl carbinols are not suitable with these highly unsaturated substrates because of their acid sensitivity. Unexpected reactivity during attempted rearrangement, including Nazarov-type electrocyclizations
Oxidation-Initiated Cyclizations of Pentadienyl Ethers: An Alternative Entry to the Nazarov Reaction
作者:Ryan J. Fradette、Minkyu Kang、F. G. West
DOI:10.1002/anie.201701748
日期:2017.5.22
Oxidation-initiatedNazarovreactions of 1,4-pentadien-3-yl ethers take place in the presence of DDQ. Termination by regioselective elimination preserves both stereocenters created during electrocyclization, providing cyclopentanone products bearing an exocyclic methylene unit. Use of catalytic DDQ with MnO2 as terminal oxidant is also described.
作者:Yonghoon Kwon、Robert McDonald、Frederick G. West
DOI:10.1002/anie.201303996
日期:2013.8.12
InternAl delivery: Organoaluminum reagents activate 1,4‐dien‐3‐ones for Nazarov electrocyclization (see scheme), then transfer a substituent to the resulting cyclopentenyl cation with moderate to complete regioselectivity and diastereoselectivity.
Intercepting the Nazarov Oxyallyl Intermediate with α-Formylvinyl Anion Equivalents to Access Formal Morita–Baylis–Hillman Alkylation Products
作者:F. West、Yen-Ku Wu、Rongrong Lin
DOI:10.1055/s-0036-1588769
日期:2017.7
catalyzed cationicdomino reaction involving sequential electrocyclization and polar addition of allenol ethers onto the resulting oxyallyl species is described. The overall sequence allows a highly stereoselective synthesis of densely substituted cyclopentanoid compounds containing α-formylvinyl functionality which is formally equivalent to products of a Morita–Baylis–Hillman alkylation process.
Interrupting Nazarov Reaction with Different Trapping Modality: Utilizing Potassium Alkynyltrifluoroborate as a σ-Nucleophile
作者:Ronny William、Siming Wang、Asadulla Mallick、Xue-Wei Liu
DOI:10.1021/acs.orglett.6b01606
日期:2016.9.16
cation intermediate generated following Nazarov cyclization of dienone has been successfully intercepted with potassium alkynyltrifluoroborates which act as σ-nucleophiles in the presence of BF3·Et2O. This new trapping modality allowed unprecedented introduction of an alkynyl moiety to the cyclopentanone framework by means of an interruptedNazarovreaction. The α-alkynyl cyclopentanone product can