General Approach for the Stereocontrolled Construction of the β-Lactam Ring in Amino Acid-Derived 4-Alkyl-4-carboxy-2-azetidinones
摘要:
The first general approach toward the asymmetric synthesis of 4-alkyl-4-carboxy-2-azetidinones derived from amino acids is described. The stereoselective construction of the beta-lactam ring was achieved through base-mediated intramolecular cyclization of the corresponding N-alpha-chloroacetyl derivatives bearing (+)- or (-)-10-(N,N-dicyclohexylsulfamoyl)isoborneol as chiral auxiliary (ee up to 82%).
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‐Alkylation of α‐Amino Esters and Amides through Hydrogen Borrowing
作者:Charlotte E. Coomber、Louis J. Diorazio
DOI:10.1002/ejoc.202200152
日期:2022.8.26
A method for the iridium catalysed direct alkylation of amino esters and amides using alcohols, which can utilise both the free base and HCl salts of the amine, was developed. This reaction proceeds through a borrowing hydrogen borrowing mechanism.
Entry to New Conformationally Constrained Amino Acids. First Synthesis of 3-Unsubstituted 4-Alkyl-4-carboxy-2-azetidinone Derivatives via an Intramolecular <i>N</i><sup>α</sup><i>-C</i><sup>α</sup>-Cyclization Strategy
作者:Guillermo Gerona-Navarro、Maria Angeles Bonache、Rosario Herranz、Maria Teresa García-López、Rosario González-Muñiz
DOI:10.1021/jo015559b
日期:2001.5.1
N-benzyl-N-chloroacetyl aminoacidderivatives is described. This study resulted in the first concise and versatile route to the preparation of 3-unsubstituted 4-alkyl-4-carboxy-2-azetidinones, to be included into the scarce family of beta-lactams with quaternary centers at the C(4) position. Particularly noteworthy is that the intramolecular N(alpha)-C(alpha)-cyclization of Phe and Leu derivatives afforded the
Cell adhesion antagonists: synthesis and evaluation of a novel series of phenylalanine based inhibitors
作者:Geraldine C.B Harriman、Charles F Schwender、Debra Gallant、Nancy A Cochran、Michael J Briskin
DOI:10.1016/s0960-894x(00)00300-0
日期:2000.7
Several phenylalanine basedinhibitors were synthesized as antagonists of the leukocyte celladhesion process that is mediated through the interactions of the mucosal addressin celladhesion molecule (MAdCAM) and the integrin alpha4beta7. Analogues 20, 21, 22 and 24 displayed inhibition of adhesion in a cellbased assay in the low micromolar range.
Protonation-Assisted Conjugate Addition of Axially Chiral Enolates: Asymmetric Synthesis of β-Lactams with Contiguous Tetrasubstituted Stereocenters from α-Amino Acids via Memory of Chirality
transformed to optically active β-lactams without the use of any external chiral sources such as chiral catalysts or chiral auxiliaries. Since β-lactams still constitute one of the most important pharmacophores, and are useful as β-amino acid equivalents and chiral building blocks, development of synthetic methods for β-lactams is still of importance. Our synthetic scheme of β-lactams by MOC strategy is shown
已经通过MOC策略开发了一种从容易获得的α-氨基酸不对称合成具有连续两个四取代立体中心的高应变β-内酰胺的方法。通过 α-氨基酸衍生物产生的轴向手性烯醇化物的 4-exo-trig 环化形成的不稳定 β-内酰胺烯醇化物中间体的原位质子化似乎是成功生产高应变 β-内酰胺的关键。这种转变的一个显着特征是质子源不会猝灭轴向手性烯醇化物 C,而是通过中间体 β-内酰胺烯醇化物 D 的质子化来加速整个反应。 引言 我们研究了通过具有动态手性的烯醇化物中间体进行的不对称反应(手性记忆:MOC)。各种类型的手性烯醇化物,在手性 CC、CN、和 CO 轴已用于 MOC 战略。该策略的主要优点是使用容易获得的 α-氨基酸作为起始材料以及手性的唯一来源。例如,天然丰富的 α-氨基酸可以在不使用任何外部手性源(如手性催化剂或手性助剂)的情况下转化为光学活性 β-内酰胺。由于β-内酰胺仍然构成最重要的药效团之一,