Radical-chain deoxygenation of tertiary alcohols, protected as their methoxymethyl (MOM) ethers, using thiols as polarity-reversal catalysts

Abstract

The deoxygenation of tertiary alcohols can be accomplished by heating their MOM ethers in the presence of a peroxide initiator and a thiol catalyst: the proposed radical-chain mechanism is supported by EPR spectroscopic studies.

Deoxygenation of tertiary and secondary alcohols ROH by thiol-catalysed radical-chain redox decomposition of derivatives ROCH2X to give RH and XCHO

“…With the aim of extending the range of electron-donating groups DR n in the alcohol derivative 4, we turned our attention to the N-alkoxymethylpyrrolidin-2-ones (PYRM ethers), which were expected to undergo thiol-catalysed radical-chain decomposition to give the deoxy compound and 1-formylpyrrolidin-2-one 26, as shown in eqn. (7). Preliminary experiments with 1-tert-butoxymethylpyrrolidin-2-one 27 were very encouraging, since this PYRM ether afforded an essentially quantitative yield of 26 after treatment with TBST and DBPC in refluxing toluene (the gaseous isobutane produced would be lost).…”

Synergistic Catalysis for the Umpolung Trifluoromethylthiolation of Tertiary Ethers

“…We found that shelf‐stable and easily available methoxymethyl (MOM)‐type tertiary alkyl ethers 1 d , 1 e could undergo the expected reaction to afford the desired product 3 a in 76 % and 57 % yields, respectively. Other substrates ( 1 a – c ) gave little or no trifluoromethylthiolation product (Scheme b).…”

Radicals in organic synthesis. Part 1

“…Roberts shown that methoxymethyl (MOM) ethers can act as good precursors if the reduction is mediated by a thiol that acts as a polarityreversal catalyst (see Section 2.5). 154 Alternatively, trifluoroacetate derivatives of tertiary alcohols such as 167 can be deoxygenated with diphenylsilane and di-tert-butyl peroxide (Scheme 47). 155 Good yields can be obtained with a variety of tertiary alcohols and it appears that reducible groups such as epoxides, ketones and esters are untouched by these reaction conditions.…”