Abstract
Tetrahydropyran (THP) rings are common in several natural products, therefore, various strategies are being developed to synthesize these rings. The present work described the study of a one-pot synthesis of 2,4,6-trisubstituted tetrahydropyran compounds promoted by the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF6] through a Barbier–Prins reaction between allyl bromide and aldehydes. The use of [BMIM][PF6] gave Prins products from several aldehydes in good yields and reaction times. We also found that the anion, PF6-, accelerates the Barbier reaction when used alone, and the excess SnBr2 from the reaction conditions of the Barbier reaction leads to the formation of the THP rings, thus acting as a catalyst for Prins cyclization. Additionally, we demonstrate that ionic liquid can be recovered and reused five times in the preparation of 4-bromo-tetrahydro-2,6-diphenyl-2H-pyran without significant yield loss.
Highlights
IntroductionA significant number of biologically important natural products contain tetrahydropyran (THP)
As reactions of hetero-Diels–Alder [10], iodolactonization reaction [11], selenium etherification of unsaturated alcohols [12], 6-endo cyclization of vinyl epoxides [13], reductive etherification [14], ring closing metathesis [15], Takeda olefination [16], SmI2 -mediated radical cyclization [17], Iterative epoxide opening cyclization [18], and Prins cyclization reaction are some synthesis methodologies developed aiming at the formation of tetrahydropyran rings
Discussion chloride dihydrate described in the Barbier protocol, using [BMIM][PF6 ] as a reaction medium under
Summary
A significant number of biologically important natural products contain tetrahydropyran (THP). The Prins cyclization is a synthetic methodology developed with the objective of forming THP rings that commonly occur between homoallylic alcohols (or ethers) and aldehydes (or acetals), primarily mediated by a Lewis acid (AlCl3 [19], SnCl4 [20], SnBr4 [21], InCl3 [22], among others). Showed that ionic liquids containing halidepromote anions the promote the of THPs rings in good yields via a one-pot. Barbier–Prins sequence of reactions; the reaction formation of formation of THPs rings in good yields via a one-pot Barbier–Prins sequence of reactions; is presence of water in the (II) in halide. Barbier reaction to using using as the the ionic ionic liquid, with the the homoallylic homoallylic alcohol product obtained with. ], the performed the allylation offrom an aldehyde aldehyde from from tetraallylstannane tetraallylstannane and homoallylic alcohol as the product in good yields.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
