Competitive Silyl–Prins Cyclization versus Tandem Sakurai–Prins Cyclization: An Interesting Substitution Effect
Autor: | Alberto Diez-Varga, Francisco J. Pulido, Asunción Barbero, Alfonso González-Ortega, Héctor Barbero |
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Rok vydání: | 2014 |
Předmět: |
Mesylates
Aldehydes Trimethylsilyl Compounds Allylic rearrangement Silylation Tandem Stereochemistry Organic Chemistry Substituent Stereoisomerism General Chemistry Prins reaction Catalysis Allyl Compounds chemistry.chemical_compound Trimethylsilyl trifluoromethanesulfonate chemistry Cyclization Alcohols Spiro Compounds Substitution effect Stereoselectivity |
Zdroj: | Chemistry – A European Journal. 20:14112-14119 |
ISSN: | 1521-3765 0947-6539 |
Popis: | Two different mechanism pathways are observed for the reaction of allylsilyl alcohols 1 and aldehydes in the presence of trimethylsilyl trifluoromethanesulfonate (TMSOTf). In the case of allylsilyl alcohols without allylic substituents, the reaction gives dioxaspirodecanes, which are the products of a tandem Sakurai-Prins cyclization. In contrast, allylsilyl alcohols with an allylic substituent (R(2)≠H) selectively provide oxepanes, thus corresponding to a direct silyl-Prins cyclization. Both types of product are obtained with excellent stereoselectivity. Theoretical studies have been performed to obtain some rationalization for the observed stereoselectivity. |
Databáze: | OpenAIRE |
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