- The rearrangements of α-imino-thioaldehydes into dihydro-1,3-thiazoles
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α-Imino-thioaldehydes were generated by retro-Diels-Alder reaction under nash vacuum thermolysis conditions. They were found to be unstable and cyclized to 2,3-dihydro-1.3-thiazoles. This cyclization was investigated by ab initio calculations.
- Arnaud,Pelloux-Leon,Ripoll,Vallee
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- Theoretical study of the cyclization of α-iminothioaldehydes into dihydrothiazoles
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When synthesized by retro-Diels-Alder reaction under flash vacuum thermolysis conditions, α-iminothioaldehydes undergo a rearrangement to 2,3-dihydro-1,3-thiazoles.These secondary enamines in turn are transformed into the more stable 2,5-dihydro-1,3-thiazoles upon standing in CDCl3 solution.The route from α-iminothioaldehydes to dihydro-1,3-thiazoles has been studied by ab initio molecular orbital theory.Geometries of stationary points on the potential energy surface were optimized using HF/6-31G(d,p) and MP2/6-31(d,p) calculations.Relative energies wereestimated using MP4STDQ calculations and the 6-31 + G(d,p) basis set and corrected for zero-point vibrational energies.Intrinsic reaction coordinate calculations at HF/6-31G(d,p) level were performed in order to check the profile of the proposed rearrangement.These calculations support the experimental findings.The most energy requiring step was found to be trans -> cis isomerization of the methylimino group -1 at the QCISD(T)/6-31 + G(d,p) level>
- Arnaud, Roger,Pelloux-Leon, Nadia,Ripoll, Jean-Louis,Valle, Yannick
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p. 1077 - 1086
(2007/10/02)
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- NEW REACTIONS WITH THIOALDEHYDES AND THIENIUM CATIONS
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i) When generated under FVT conditions α-imino-thioaldehydes undergo a cyclization to dihydro-1,3-thiazoles. ii) Thienium cations, generated during a Pummerer reaction, can be trapped with dienes.
- Arnaud, Roger,Chavant, Pierre-Yves,Hagoug, Fatiha,Pelloux-Leon, Nadia,Ripoll, Jean-Louis,Vallee, Yannick
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p. 319 - 320
(2007/10/02)
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- Synthesis of dolastatin 10
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A complicated but extremely important scheme of synthesis has been developed for synthesizing, dolaisoleuine, dolaproine, dolaphenine and dolavaline from readily available starting materials such as Z-(S,S)isoleucine, S-phenylalaline, S-phenylalaninol, S-prolinol, S-mandelate, and S-valine. The requisite amino acids have been combined using several peptide coupling procedures to create pharmaceutically pure dolastatin 10.
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