Highly Diastereofacial <i>Anti</i>-Aldol Reaction: Practical Synthesis of Optically Active <i>anti</i>-2-Alkyl-3-Hydroxycarboxylic Acid Ester Units
作者:Michio Kurosu、Miguel Lorca
DOI:10.1021/jo001293h
日期:2001.2.1
variety of esters derived from commercially available norephedrine were used in diastereoselective anti-aldol reactions. The aldolreaction of designed 2-(N-2-methylbenzyl-N-2,4,6-trimethylbenzyl)amino-1-phenylpropanol esters 4a-d with aldehydes furnished anti-2-alkyl-3-hydroxycarboxylic acid esters in excellent diastereomeric ratios (>98:2) when LDA-Cp2ZrCl2 (0.3 equiv) was used for enolization, followed
The TEMPO-mediated oxidative deformylation of aldehydes is reported that yields the TEMPO adducts which can be further oxidized to the corresponding ketones. The focus of this work was on the optimization of a synthetic protocol for use in natural product synthesis, specifically for the preparation of chiral backbones with 1,2-oxo functionalization found in polyketide antibiotics. In addition, the
据报道,TEMPO 介导的醛氧化去甲酰化产生的 TEMPO 加合物可以进一步氧化成相应的酮。这项工作的重点是优化用于天然产物合成的合成方案,特别是用于制备在聚酮抗生素中发现的具有 1,2-氧代官能化的手性骨架。此外,在一锅法中将氧化去甲酰化与醇氧化成前体醛相结合。
Substrate-controlled stereoselectivity in the Yamamoto aldol reaction
作者:Nadin Schläger、Andreas Kirschning
DOI:10.1039/c2ob26185e
日期:——
The Yamamoto aldol reaction is a vinylogous aldol reaction that relies on bulky aluminium-based Lewis acids. These activate both the aldehyde as well as become part of the enolate moiety. The report discloses the first detailed study on the substrate-controlled Yamamoto aldol reaction in which 2,3-syn and 2,3-anti disubstituted aldehydes serve as the stereodirecting elements. The “size” of the substituent in the β-position strongly determines the facial selectivity of enolate addition to the aldehyde. Large substituents favour formation of 1,3-syn diols while slim alkynyl groups preferentially lead to 1,3-anti products.
Ruthenium hydride catalyzed silylvinylation of terminal alkynes under ethylene atmosphere at 80 psi
作者:Alexandre D.C. Dixon、Robert J. Wilson、Daniel D. Nguyen、Daniel A. Clark
DOI:10.1016/j.tetlet.2017.09.023
日期:2017.10
The development of methods for the stereoselectivesynthesis of polysubstituted 1,3-dienes is a challenge to synthetic chemistry. Herein is reported a selective approach for the synthesis of polysubstituted 1,3-dienes using the ruthenium hydride catalyzed intramolecular silylvinylation of alkynes under 80 psi of ethylene gas. This strategy affords a single diene isomer, is applicable to substrates
Manipulation of the aldol adducts from lactate-derived ketones. A versatile chiral auxiliary for the asymmetric synthesis of β-hydroxy carbonyl compounds
作者:Ian Paterson、Debra J. Wallace
DOI:10.1016/0040-4039(94)88435-8
日期:1994.11
The ketones 1 and 2 can be transformed into a wide range of enantiomerically-pure anti and syn α-methyl-β-hydroxy ketones and aldehydes. The α′-methyl group in 5 and 11 may be retained, demonstrating the use of the lactate-derived group as an optional chiral auxiliary.