Asymmetric Synthesis of <i>anti</i>-β-Amino-α-Hydroxy Esters via Dynamic Kinetic Resolution of β-Amino-α-Keto Esters
作者:C. Guy Goodman、Dung T. Do、Jeffrey S. Johnson
DOI:10.1021/ol4009206
日期:2013.5.17
method for the asymmetricsynthesis of enantioenriched anti-α-hydroxy-β-amino acid derivatives by enantioconvergent reduction of the corresponding racemic α-keto esters is presented. The requisite α-keto esters are prepared via Mannich addition of ethyl diazoacetate to imines followed by oxidation of the diazo group with Oxone. Implementation of a recently developed dynamickinetic resolution of β-substituted-α-keto
A novel one-pot, three-component synthesis of N-acyl or N-carbamoyl-alpha-amidosulfides 4 is described. The three-component reaction of aldehydes 1, primary carbamates (or amides) 2 and phenylsulfinic acid (6a) afforded alpha-amidosulfones 7, which after addition of sodium thiolate were in situ transformed into stable alpha-amidosulfides 4 in good to excellent yields. We demonstrated that silver salts
Asymmetric Disulfonimide-Catalyzed Synthesis of δ-Amino-β-Ketoester Derivatives by Vinylogous Mukaiyama-Mannich Reactions
作者:Qinggang Wang、Manuel van Gemmeren、Benjamin List
DOI:10.1002/anie.201407532
日期:2014.12.1
organocatalytic asymmetricsynthesis of δ‐amino‐β‐ketoester derivatives has been developed. A chiral disulfonimide (DSI) serves as a highly efficient precatalyst for a vinylogous Mukaiyama–Mannich reaction of readily available dioxinone‐derived silyloxydienes with N‐Boc‐protected imines, delivering products in excellent yields and enantioselectivities. The synthetic utility of this reaction is illustrated
Enantioselective Mannich Reaction of β-Keto Esters with Aromatic and Aliphatic Imines Using a Cooperatively Assisted Bifunctional Catalyst
作者:Antti J. Neuvonen、Petri M. Pihko
DOI:10.1021/ol5025025
日期:2014.10.3
An efficient urea-enhanced thiourea catalyst enables the enantioselective Mannichreaction between β-keto esters and N-Boc-protected imines under mild conditions and minimal catalyst loading (1–3 mol %). Aliphatic and aromatic substituents are tolerated on both reaction partners, affording the products in good enantiomeric purity. The corresponding β-amino ketones can readily be accessed via decarboxylation
Triethylborane-mediated tin-freeradical alkylation of N-alkoxycarbonyl-imines, such as N-Boc-, N-Cbz-, and N-Teoc-imines, proceeded smoothly at a low temperature (−78 to −20 °C) to give the corresponding adducts in high yield. Although the formation of isocyanate was the major unfavorable reaction at room temperature, a one-pot conversion of N-Boc-imine to N-ethoxycarbonyl-adduct was possible through