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

Abstract

A mild and efficient procedure for the oxyselenocyclization of unsaturated alcohols by treatment with phenylselenyl chloride using ionic liquids as solvents/catalyzers has been developed. The reaction proceeds instantaneously under mild conditions with absolute regioselectivity, using primary, secondary, tertiary, and aromatic alcohols, as well as monosubstituted, disubstituted, and trisubstituted alkenols. This procedure provides a new method for the synthesis of substituted tetrahydrofurans and tetrahydropyrans ethers, the precursors of many biologically active metabolites, avoiding the use of toxic and corrosive catalysts. There are no previous reports of seleniummediated cyclofuncionalization reactions in ionic liquids. Taking into the account the good results obtained with [MMIM][MSO 4 ], its ease preparation, low viscosity, low price, and its capacity to be recovered and reused, it was selected as the solvent/catalyzer. Quantum-chemical calculations (MP2(fc)/ 6-311 + G**//B3LYP/6-311 + G**) has shown that the intramolecular cyclization is promoted by the hydrogen bond formed between the ionic liquid anion and the hydroxyl group of the alkenol.

Oxyselenocyclization of 2‐Allylphenols for the Synthesis of 2,3‐Dihydrobenzofuran Selenides

“…Based on the control experiments and in the literature, [89,[73][74][75][76] a plausible mechanism for the formation of 2-[(phenylselanyl)methyl]-2,3-dihydrobenzofuran 3 a from the reaction of 2-allylphenol 1 a and diphenyl diselenide 2 a promoted by Oxone® is presented in Scheme 2. Firstly, diphenyl diselenide 2 a reacts with Oxone® to affords two electrophilic selenium species, A and B.…”

“…Thus, the method to deliver 2‐[(organoselanyl)methyl]‐2,3‐dihydrobenzofurans consists in the intramolecular oxyselenation of 2‐allylphenols 1 with an electrophilic selenium species (Scheme 1A). The first described method to achieve this transformation relied on the reaction between substrate 1 and excess of phenylselanyl chloride (C 6 H 5 SeCl) [86–89] . Although being efficient, this approach suffers from the use of C 6 H 5 SeCl, a reagent that imposes many hazards in terms of transport, storage and handling owing to its high toxicity.…”

“…The first described method to achieve this transformation relied on the reaction between substrate 1 and excess of phenylselanyl chloride (C 6 H 5 SeCl). [86][87][88][89] Although being efficient, this approach suffers from the use of C 6 H 5 SeCl, a reagent that imposes many hazards in terms of transport, storage and handling owing to its high toxicity. Later on, combinations of diphenyl diselenide and oxidizing agents, to produce in situ the necessary electrophilic selenium species to promote the cyclization step, were explored.…”

Automated Electrochemical Selenenylations

“…The spectral data are in agreement with the literature. 21 1 H NMR (500 MHz, CDCl 3 ):  = 7.59-7.54 (m, 2 H), 7.30-7.23 (m, 3 H), 4.51 (d, J = 4.9 Hz, 1 H), 3.90 (ddd, J = 11.2, 7.4, 3.6 Hz, 1 H), 3.58-3.49 (m, 1 H), 3.42 (s, 3 H), 3.27 (dt, J = 7.4, 4.6 Hz, 1 H), 2.20 (ddd, J = 16.9, 8.1, 3.9 Hz, 1 H), 1.86-1.68 (m, 2 H), 1.57-1.48 (m, 1 H).…”