Enantioselective synthesis of non-proteinogenic amino acids via metallated bis-lactim ethers of 2,5-diketopiperazines
作者:Ulrich Schöllkopf
DOI:10.1016/s0040-4020(01)91926-x
日期:1983.1
excess = asymmetric induction) of the adduct exceeds 95%. On hydrolysis the adducts are cleaved liberating the chiral auxiliary (used to build up the bis-lactim ether 1) and the target molecules, the opticallyactive amino acid methyl esters of type 8,19,25 or 36. The two amino acid esters are separable either by fractional distillation or (eventually after further hydrolysis to amino acids) by chromatography
Lewis Acid-Catalyzed Halonium Generation for Morpholine Synthesis and Claisen Rearrangement
作者:Jeewani P. Ariyarathna、Nur-E Alom、Leo P. Roberts、Navdeep Kaur、Fan Wu、Wei Li
DOI:10.1021/acs.joc.1c02804
日期:2022.3.4
We disclose here practical strategies toward the synthesis of morpholines and Claisenrearrangement products based on the divergent reactivity of a common halonium intermediate. These reactions employ widely available alkenes in a Lewis acid-catalyzed halo-etherification process that can then transform them into the desired products with exceptional regioselectivity for both activated and unactivated
KEMPE, MARIA;EKBERG, BJORN;MOSBACH, KLAUS, INT. J. PEPTIDE AND PROTEIN RES., 35,(1990) N, C. 147-152
作者:KEMPE, MARIA、EKBERG, BJORN、MOSBACH, KLAUS
DOI:——
日期:——
Cyclic Dipeptides. 3.<sup>1</sup> Synthesis of Methyl (<i>R</i>)-6-[(<i>tert</i>-Butoxycarbonyl)amino]-4,5,6,7- tetrahydro-2-methyl-5-oxo-1,4-thiazepine-3-carboxylate and Its Hexahydro Analogues: Elaboration of a Novel Dual ACE/NEP Inhibitor
Syntheticroutes to highly functionalized 1,4-thiazepinones 2 and 3 have been developed. S-Ac-N-Boc-L-Cys-D(L)-ThrOMe 7a,b have been prepared and, after transformation into the corresponding mesylates, used as the cyclization substrates. Treatment of these compounds with LiAlH(OMe)(3) in THF results in mesylate elimination and thiolacetate reduction, giving rise to both a Michael acceptor (alpha,beta-unsaturated