Efficient synthetic methods for unsaturated 3,4,5-trimethoxybenzyl sulfides and ethers

Acetylene in Organic Synthesis: Recent Progress and New Uses

“…An effective vinylation methodology for 3,4,5-trimethoxybenzyl alcohol ( 5 ) was proposed [ 61 ]. The resulting 3,4,5-trimethoxybenzyl vinyl ether ( 6 ) is a promising starting material for drug synthesis.…”

“…Using CaC 2 instead of gaseous acetylene provides certain economy, as only 2.5 to 3.3-fold excess of it is required to complete the reaction. Similar reactions with gaseous acetylene (see Scheme 3 , Scheme 4 and Scheme 5 ) were carried out under high acetylene pressures (10-13 atm) or in acetylene flow [ 61 , 62 , 63 ].…”

“…Another reaction, which is also acetylene-dependent, allows obtaining vinyl chalcogenides from disulfides, diselenides, and ditellurides; it leads to vinyl sulfides, vinyl selenides, and vinyl tellurides, respectively. It has several reported implementations [ 61 , 83 , 84 ]. The first resulted from interaction of a dichalcogenide 35 with gaseous acetylene in the presence of a reducing agent, e.g., hydrazine-KOH mixture or sodium borohydride.…”

“…The first resulted from interaction of a dichalcogenide 35 with gaseous acetylene in the presence of a reducing agent, e.g., hydrazine-KOH mixture or sodium borohydride. To complete the reaction, the presence of the reducing agent is required ( Scheme 15 ) [ 61 , 84 ]. Using this methodology, the corresponding vinyl chalcogenides 36 were obtained in excellent yields.…”

“…Another variation on the theme was recently proposed [ 61 , 83 , 84 ]. In this setting, alkyl or aryl halide was directly exposed to sulfur, selenium or tellurium one-flask with a reducing agent and acetylene.…”