Application of the Brook Rearrangement in Tandem with Single Electron Transfer Oxidative and Radical Processes
作者:Mikhail K. Klychnikov、Radek Pohl、Ivana Císařová、Ullrich Jahn
DOI:10.1002/ejoc.202000126
日期:2020.5.22
Rearrangement and radical puzzle: Chiral epoxides, silylated acetamides, and stable radical TEMPO provide, with the help of ferrocenium hexafluorophosphate, dioxygenated carbonylcompounds, which serve as versatile radical cyclization precursors.
Synthesis of 3-aryl- or 3-alkenyl-4,6-dimethyl-2-pyrones by silver ion promoted rearrangement of 4-aryl- or4-alkenyl-3-bromo-4,6-dimethyl-3,4-dihydro-2-pyrones
Debromination of 4-aryl- or 4-alkenyl-3-bromo-4,6-dimethyl-3,4-dihydro-2-pyrone () with AgSbF6 in dichloromethane or 1,2-dichloroethaneinduced rearrangement of the aryl or alkenyl group to the 3-position to afford the corresponding 3-substituted 2-pyrone () in high yield.
A mechanistic and synthetic study of organocopper substitution reactions with some homoallylic and cyclopropylcarbinyl substrates
作者:G.H. Posner、J-S. Ting、C.M. Lentz
DOI:10.1016/0040-4020(76)88002-7
日期:1976.1
cyclopropylmethylcarbinyl tosylate participate in organocuprate substitution reactions; retention of configuration at the nucleofugal sp3-C atom and skeletal reorganizations are observed. A plausible mechanism for these reactions is discussed. Coupling of homogeranyl iodide with a four-carbon, functionalized, vinylic cuprate reagent is applied to stereospecificsynthesis of trans, trans-farnesol.
A short enantiospecific synthesis of the ceroplastin nucleus.
作者:Barry B. Snider、Ke Yang
DOI:10.1021/jo00039a021
日期:1992.6
The tricyclic nucleus 9b of ceroplastol I and ceroplasteric acid has been synthesized stereoselectively and enantiospecifically in only 10 steps from 1-cyclopentenecarboxaldehyde. Addition of (3-methyl-3-butenyl)magnesium bromide to imine 13b and methylation with methyl iodide by Koga's procedure gave 94% of optically pure aldehyde 40 as previously described in our reiswigin A synthesis. Isomerization of the double bond of aldehyde 40 with HI afforded aldehyde 17b. Coupling of the enolate prepared from silyl enol ether 45 with aldehyde 17b gave a 1:1 mixture of 46a and 46b, which contain the complete carbon skeleton of 9b, in only three steps. Dehydration provided enones 47a and 47b. Reduction of 47a and 47b with Li/NH3 afforded saturated ketones 48at and 48bt that were reduced with LiAlH4 to the saturated alcohols 49att and 49btt. Protection of the alcohols as the TBDMS ethers and oxidative cleavage of the dienes afforded readily separable keto aldehydes 51 and 56. McMurry coupling of 51, cleavage of the silyl ether, and oxidation of the alcohol with PCC completed the synthesis of 9b.
Tandem Cope-Claisen rearrangement. Scope and stereochemistry