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Catalytic, Asymmetric Transannular Aldolizations: Total Synthesis of (+)-Hirsutene
作者:Carley L. Chandler、Benjamin List
DOI:10.1021/ja8024164
日期:2008.5.1
We report an asymmetric, catalytic transannular aldolization that provides polycyclic products useful for natural product synthesis. We found that a proline-derivative catalyzes the transannular aldol reaction of 1,4-cyclooctanediones to the corresponding cyclic beta-hydroxy ketones in good yields and with high enantioselectivities. The utility of our reaction has been demonstrated in a total synthesis
Rhodium(II)-carbenoid C–H insertion reactions in the synthesis of β-oxospirane systems
作者:Pompiliu S. Aburel、Kjell Undheim
DOI:10.1039/b001988g
日期:——
A simple one-pot procedure is described for the preparation of spiro[4.4]nonane-2,7-dione derivatives from open chain bis(α-diazoketones) by two consecutive intramolecular Rh(II)-catalyzed carbenoid insertion reactions. With 1-diazo-4-(3-oxocycloalkyl)butan-2-ones as substrates, the methodology provides 2,7-dioxospiranes with a cyclopentane ring spiroannulated onto a five-, six- or seven-membered cycloalkane.
Synthesis of spirosystems by rhodium(II)-carbenoid CH insertion reactions
作者:Pompiliu S. Aburel、Kjell Undheim
DOI:10.1016/s0040-4039(98)00591-7
日期:1998.5
preparation of spiro[4,4]nonane-2,7-dione derivatives from open chain bis(α-diazoketones). The reactions proceed by an intramolecular Rh(II)-carbenoid insertion into a methylene CH bond yielding a cyclopentane which subsequently undergoes CH methine insertion and cyclopentyl spiroannulation.
Synthesis of some medium- and large-ring cycloalk-2-ene-1,4-diones by intramolecular coupling of αω-bis-diazoketones
作者:Sunanta Kulkowit、M. Anthony McKervey
DOI:10.1039/c39780001069
日期:——
In the presence of Cu(acac)2(Hacac = acetylacetone) someαω-bis-diazoketones couple intramolecularly with loss of nitrogen giving cycloalk-2-ene-1,4-diones; the enediones can be converted into fused ring cyclopentenones by successive treatment with sodium dithionite and sodium hydroxide.