Intramolecular additions of allylsilanes to conjugated dienones. Direct stereoselective syntheses of (.+-.)-neolemnanyl acetate and (.+-.)-neolemnane
摘要:
The total synthesis of the marine sesquiterpenes neolemnanyl acetate (1) and neolemnane (2) is reported. An intramolecular allylsilane addition to a conjugated dienone is used to assemble the basic 6,8-fused skeleton. Functionalization of the cyclooctane ring was achieved by means of a regiospecific photooxygenation.
Synthesis of the Oxygenated Bicyclo[9.3.1]pentadecane Ring System of Phomactin A using Chromium (II)-mediated Macrocyclisation and Ring Closure Metathesis
作者:Kevin M. Foote、Matthew John、Gerald Pattenden
DOI:10.1055/s-2001-11403
日期:——
Treatment of the aldehyde vinyl iodides 17, 19 a and 19 b in DMSO with CrCl2-NiCl2 resulted in their macrocyclisation to the oxygenated ring systems 18, 20, and 21 respectively (43-63%) of the PAF antagonist phomactin A isolated from the marine fungus Phoma sp. The same bicyclo[9.3.1]pentadecane ring system 24 could also be produced by treatment of the polyene 23 with Grubbs' ruthenium catalyst in hot CH2Cl2 for 10 h (∼ 30%).
Formal synthesis of (±)-upial. Oxidative free-radical cyclization of unsaturated 1,3-cyclohexanediones
作者:Barry B. Snider、Steven V. O'Neil
DOI:10.1016/0040-4020(95)00841-u
日期:1995.11
Oxidative free-radicalcyclization of 4-(3-hexcnyl)-1,3-cyclohexanedione 8 affords 85% of a mixture of 7 and 29. Short sequences were developed to convert this mixture to 2, a late intermediate in Taschner's synthesis of upial.
Synthetic studies towards the phomactins. Concise syntheses of the tricyclic furanochroman and the oxygenated bicyclo[9.3.1]pentadecane ring systems in phomactin A
作者:Kevin M Foote、Christopher J Hayes、Matthew P John、Gerald Pattenden
DOI:10.1039/b307985f
日期:——
A concise synthesis of the tricyclic furanochroman unit 3 found in the PAF antagonist phomactin A (1) isolated from the marine fungus Phoma sp., is described. In complementary studies, a variety of synthetic routes towards the bicyclo[9.3.1]pentadecaneringsystem 4 in phomactin A were explored. These studies culminated in a synthesis of the substituted ringsystem 79 containing all the carbon atoms
The total synthesis of the marine sesquiterpenes neolemnanyl acetate (1) and neolemnane (2) is reported. An intramolecular allylsilane addition to a conjugated dienone is used to assemble the basic 6,8-fused skeleton. Functionalization of the cyclooctane ring was achieved by means of a regiospecific photooxygenation.