Isomerization of Trimethyl α-Keto Trithioorthocarboxylates into α,α-Bis(methylthio) Thiolcarboxylates. A New Rearrangement of Synthetic Interest
摘要:
A study was made of the isomerization reaction of a great variety of trimethyl alpha-keto trithioorthocarboxylates to alpha,alpha-bis(methylthio) thiolcarboxylates, intermediates of high synthetic value for the synthesis of alpha-arylpropionic acids. The reaction was carried out In methylene chloride in the presence of catalytic amounts of trityl perchlorate or methanesulfonic acid and was complete in 2 h at rt. In most of the investigated cases the result was positive, the yields usually being greater than 90%. Also the reaction mechanism was subjected to an experimental study.
of the α-imino thioester was examined, and we found that α-imino thioesters were more effective substrates for the umpolung N-alkylation than conventional α-imino esters and they gave N-alkylated amino thioesters in high yields under mild reaction conditions in a short time. A new type of C–Cbondformation followed by an unexpected rearrangement of the alkylthio group took place with the unsaturated
Direct Access to 2-Thioxooxazolidin-4-ones and Oxazolidine-2,4-diones from α-Keto Thioesters through Thiolate Transfer
作者:Rajib Maity、Sandip Naskar、Kanchan Mal、Sandipa Biswas、Indrajit Das
DOI:10.1002/adsc.201701020
日期:2017.12.19
We report a direct synthesis of 2‐thioxooxazolidin‐4‐ones and oxazolidine‐2,4‐diones from α‐keto thioesters with sodium thiocyanate or potassiumcyanate, respectively. The reactions proceed through nucleophilic substitution of a thioester with thiocyanate/cyanate anion, thiolate anion addition to carbonyl carbon, and subsequent intramolecular C−O heterocyclization.
Tandem Chemoselective 1,2-/1,4-Migration of the Thio Group in Keto Thioesters: An Efficient Approach to Substituted Butenolides
作者:Kanchan Mal、Sandip Naskar、Shovan Kumar Sen、Ramalingam Natarajan、Indrajit Das
DOI:10.1002/adsc.201600640
日期:2016.10.20
We report herein an efficient and mechanistically unique tandem chemoselective 1,2‐/1,4‐migration of the thio group in keto thioesters that provides substitutedbutenolides in moderate to excellent yields. Thus, α‐keto thioesters in the presence of stabilized phosphonate carbanions undergo tandem 1,2‐sulfur migration; whereas 1,4‐migration of the thio group has been achieved with the same thioesters
Photochemical reactions of mercapto/amino substituted alkyl phenylglyoxylates induced by intramolecular electron transfer
作者:Shengkui Hu、Douglas C. Neckers
DOI:10.1016/s0040-4020(97)00044-6
日期:1997.2
normal NorrishtypeII cleavage products, the title compounds undergo intermolecular electrontransfer from the heteroatom (sulfur/nitrogen) to the excited carbonyl group, followed by proton transfer and subsequent closing of the resulting biradicals to produce seven-membered (2)/five-membered (11) lactones in high yield. Thiadialkyl phenylglyoxylates (9) react inefficiently due to intramolecular self-quenching