Ethylene

Vinyl Thianthrenium Tetrafluoroborate: A Practical and Versatile Vinylating Reagent Made from Ethylene

“…Ethylene is an inexpensive gas (annual production >100 million tons), 7 but its use in organic synthesis is rare and typically limited to simple substrates without high levels of complexity. 8 One of the main drawbacks of the use of ethylene is the high temperature and pressures that are generally required for its conversion. In fact, reactions engaging ethylene at atmospheric pressure (1 atm) are uncommon and almost exclusive to metal-mediated reactions, owing to the ability of metal centers to activate ethylene via coordination.…”

“…Ethylene is an inexpensive gas (annual production >100 million tons), but its use in organic synthesis is rare and typically limited to simple substrates without high levels of complexity . One of the main drawbacks of the use of ethylene is the high temperature and pressures that are generally required for its conversion.…”

“…The perchlorate salt of vinyl-TT + was published three decades ago while exploring the reactivity of thianthene radical cation (TT •+ ) with (vinyl) 4 Sn, but only milligram quantities were accessed owing to the involvement of potentially explosive perchlorate salts, and its synthetic use has never been reported. While, in comparison with other olefins, ethylene gas typically requires high pressure and an autoclave for cycloaddition reactions, , we sought to capitalize on the high reactivity of the highly electrophilic thianthrenium dication species generated by treatment of thianthrene- S -oxide ( 2 ) with activating reagents such as Tf 2 O (Figure A). Following our new protocol, vinyl thianthrenium tetrafluoroborate ( 1 ) can now be prepared on multigram scale (50 mmol) with a simple balloon of ethylene (1 atm) in 86% yield.…”