Phenylsulfenyl chloride/N,N-diisopropylethylamine: A useful reagent for cyclic ether formation (sulfenyletherification)
作者:Sudersan M Tuladhar、Alex G Fallis
DOI:10.1016/s0040-4039(00)95772-1
日期:1987.1
A general method for the formation of cyclicethers and lactones is described. The procedure employs phenylsulfenyl chloride and N,N-diisopropylethylamine to generate an episulfonium ion intermediate from which the cyclic products arise by internal nucleophilic displacement.
Stereoselective [4+2]‐Cycloaddition with Chiral Alkenylboranes
作者:Dongshun Ni、Brittany P. Witherspoon、Hong Zhang、Chen Zhou、K. N. Houk、M. Kevin Brown
DOI:10.1002/anie.202000652
日期:2020.7.6
A method for the stereoselective [4+2]‐cycloaddition of alkenylboranes and dienes is presented. This transformation was accomplished through the introduction of a new strategy that involves the use of chiral N‐protonated alkenyl oxazaborolidines as dieneophiles. The reaction leads to the formation of products that can be readily derivatized to more complex structural motifs through stereospecific transformations
Fragmentation of Homoallylic Alkoxides. Preparation of 1-(3?-cyclopentenyl)-2-alkanones from 2-substituted bicyclo[2.2.1]hept-5-en-2-ols
作者:Roger L. Snowden
DOI:10.1002/hlca.19830660405
日期:1983.6.15
The potassium 2-substituted bicyclo[2.2.1]hept-5-en-2-alkoxides derived from alcohols 2–9 at 30° in hexamethylphosphoric triamide (HMPA) afford 1-(3′-cyclopentenyl)-2-alkanones 10–19via heterolytic C(1), C(2)-allylic bond cleavage in the substrate alkoxide followed by intramolecular protonation of the resultant transient allylic anion.
Diels-Alder reactions of 2-Alkenylboranes and cis-1-alkenylboranes. Anomalous selectivity that allows a choice of regiochemistry
作者:Daniel A. Singleton、Kyeongsook Kim、Jose P. Martinez
DOI:10.1016/s0040-4039(00)93382-3
日期:1993.5
2-Alkenyl- and cis-1-alkenylboranes are highly reactive Diels-Alder dienophiles which display unusual selectivity patters. By taking advantage of a reversal of regiochemistry of reaction with alkenyldihalo- versus alkenyldialkylboranes, any desired regioisomeric product may be favored, usually with very high selectivity.
Diels–Alder reactions of pinacol alkenylboronates: an experimental and theoretical study
作者:Margarita M. Vallejos、Nicolás Grimblat、Silvina C. Pellegrinet
DOI:10.1039/c4ra07415g
日期:——
We have studied the Diels–Alder reactions of pinacol alkenylboronates with cyclopentadiene under two different sets of conditions: thermal heating at 170 °C in a pressure tube and with catalytic TFA (5 mol%) at 80 °C. Yields varied significantly from system to system and also for the uncatalyzed and catalyzed methodologies. Moderate to excellent exo-stereoselectivities were obtained in all cases. The