61668-14-2Relevant articles and documents
Gaining Insight Into Reactivity Differences Between Malonic Acid Half Thioesters (MAHT) and Malonic Acid Half Oxyesters (MAHO)
Bew, Sean P.,Stephenson, G. Richard,Rouden, Jacques,Godemert, Jeremey,Seylani, Haseena,Martinez-Lozano, Luis A.
supporting information, p. 4557 - 4569 (2017/04/13)
An efficient two-step synthesis of structurally and functionally diverse thiophenol- and (cyclo)alkyl-derived malonic acid half thioesters (MAHTs) and phenol-derived malonic acid half oxyesters (MAHOs) has been achieved using cheap, readily available and easily handled starting materials. The synthesis of the MAHTs and MAHOs (the majority of which have not been previously reported) is readily scalable to afford gram quantities of product. In a hydrogen→deuterium exchange, an interesting stereoelectronic effect was observed when different aryl groups were incorporated. Significant changes in the rates of hydrogen→deuterium exchange and levels of isotope incorporation were observed. By way of example, using [2H]methanol and 4-bromophenol-derived MAHO afforded only 14 % [2H]-incorporation (9 min, k=31) whereas the corresponding 4-bromothiophenol-derived MAHT afforded 97 % [2H]-incorporation (9 min, k=208). In a benchmark procedure and comprehensive DFT study, 54 ester and thioester configurations and conformations were characterized. In the MAHT series, a sulfur-containing molecular orbital provides a path for increased delocalisation of electron density into the enol that is unavailable in MAHOs. This facilitates keto–enol tautomerisation and consequently enhances the rate and percentage of hydrogen→deuterium exchange.
Expanding the utility of Bronsted base catalysis: Biomimetic enantioselective decarboxylative reactions
Pan, Yuanhang,Kee, Choon Wee,Jiang, Zhiyong,Ma, Ting,Zhao, Yujun,Yang, Yuanyong,Xue, Hansong,Tan, Choon-Hong
supporting information; experimental part, p. 8363 - 8370 (2011/09/13)
As a result of the low reactivity of simple esters, the use of them as nucleophiles in direct asymmetric transformations is a long-standing challenge in synthetic organic chemistry. Nature approaches this difficulty through a decarboxylative mechanism, which is used for polyketide synthesis. Inspired by nature, we report guanidine-catalyzed biomimetic decarboxylative C-C and C-N bond-formation reactions. These highly enantioselective decarboxylative Mannich and amination reactions utilized malonic acid half thioesters as simple ester surrogates. It is proposed that nucleophilic addition precedes decarboxylation in the mechanism, which has been investigated in detail through the identification of intermediates by using electrospray ionization (ESI) mass-spectrometric analysis and DFT calculations. Copyright
An exceptionally mild catalytic thioester aldol reaction inspired by polyketide biosynthesis
Lalic, Gojko,Aloise, Allen D.,Shair, Matthew D.
, p. 2852 - 2853 (2007/10/03)
This report details our discovery of a new catalytic ester aldol reaction using malonic acid half thioesters (MAHTs) that directly affords β-hydroxythioesters. The reaction is catalyzed by combination of a Cu(II) salt and an amine base, and it can be perf
