Alkene selenenylation: A comprehensive analysis of relative reactivities, stereochemistry and asymmetric induction, and their comparisons with sulfenylation

Abstract

SummaryA broad perspective of various factors influencing alkene selenenylation has been developed by concurrent detailed analysis of key experimental and theoretical data, such as asymmetric induction, stereochemistry, relative reactivities, and comparison with that of alkene sulfenylation. Alkyl group branching α to the double bond was shown to have the greatest effect on alkene reactivity and the stereochemical outcome of corresponding addition reactions. This is in sharp contrast with other additions to alkenes, which depend more on the degree of substitution on C=C or upon substituent electronic effects. Electronic and steric effects influencing asymmetric induction, stereochemistry, regiochemistry, and relative reactivities in the addition of PhSeOTf to alkenes are compared and contrasted with those of PhSCl.

Natural Compounds and Their Structural Analogs in Regio- and Stereoselective Synthesis of New Families of Water-Soluble 2H,3H-[1,3]thia- and -Selenazolo[3,2-a]pyridin-4-ium Heterocycles by Annulation Reactions

“…Besides, the formation of thiiranium and seleniranium species determines the reaction course as anti-addition in reactions of sulfenyl and selenenyl halides with alkenes. For example, the known reactions of arylsulfenyl and arylselenenyl chlorides with cycloalkenes proceeded as anti-addition affording adducts with trans-configuration [55][56][57][58]. The anti-addition was also observed in the reactions of 2-pyridinesulfenyl and selenenyl halides with isoeugenol, methyl isoeugenol, and trans-anethole affording products 6, 8, 11-13, 16 with trans-configuration.…”

A mild and efficient procedure for alkenols oxyselenocyclization by using ionic liquids

“…The later intramolecular nucleophilic attack of the hydroxyl group at one of the carbons of the seleniranium ring gives the cyclic ether product. As result of the seleniranium intermediate formation, the reaction is antistereospecific . Depending on the chain length and the substitution pattern of the alkenol, the reaction can follow an exo‐ and/or endo‐pathway to give a five or a six membered cyclic ether (Scheme ).…”

Light‐Driven Single‐Electron Transfer Processes as an Enabling Principle in Sulfur and Selenium Multicatalysis

“…In an ensuing series of mechanistic investigations it was found that these reactions proceed through a radical‐polar crossover (RPC) mechanism, in which the Se catalysts function as redox transmitters between the single‐electron regime of the photocatalysts and the two‐electron regime of the bond‐forming event between the alkenes and the nucleophiles . Taking into account that selenium‐π‐acid‐catalyzed olefin functionalizations predominantly proceed with high Markovnikov regioselectivity, this method provides an orthogonal entry to the functionalization of alkenes compared with the strategies discussed above. According to the authors proposal, diselenide catalyst 69 undergoes a SET with photoexcited pyrylium ion 80 .…”