ortho-Lithiation of S-tert-butyl-S-phenylsulfoximines. New route to enantiopure sulfinamides via a de-tert-butylation reaction
摘要:
The sulfoximine group proved to be an excellent ortho-directing group in lithiation reactions. Several electrophiles were used to afford the corresponding ortho-functionalized aryl sulfoximines in good yields. The use of prochiral electrophiles lead to modest to good diastereoselectivities up to 95%. During this study, we observed a side reaction due to a S-de-tert-butylation. After optimization of this S-de-tert-butylation reaction, the corresponding enantiopure sulfinamides could be obtained in good yields. (c) 2005 Elsevier Ltd. All rights reserved.
Ring‐Closing Metathesis of Sulfoximine‐Substituted N‐Tethered Trienes: Modular Asymmetric Synthesis of Medium‐Ring Nitrogen Heterocycles
作者:Vishal Mahajan、Hans‐Joachim Gais
DOI:10.1002/chem.201003172
日期:2011.5.23
A synthesis of sulfoximine‐substituted medium‐ring nitrogen heterocycles (MRNHs) having a high degree of substitution has been developed. Its key steps are the modular asymmetric synthesis of sulfoximine‐substituted N‐tethered trienes and their Ru‐catalyzed ring‐closing metathesis (RCM) reaction. The highly substituted N‐tethered trienes were obtained enantio‐ and diastereopure through 1) the diastereoselective
已开发出具有高取代度的亚磺酰亚胺取代的中环氮杂环(MRNH)的合成。它的关键步骤是磺酰亚胺亚胺取代的N系三烯的模块化不对称合成及其Ru催化的闭环复分解(RCM)反应。通过1)磺基肟-取代allyltitanium复合物与非对映选择性氨基烷基化,得到对映和diastereopure高度取代的N-拴三烯ñ -叔-butylsulfonyliminoester,2)Ñ的高烯丙基-allylation Ñ-磺胺,3)α-硫代烯基磺酰亚胺亚胺的烯丙基化,羟烷基化和甲酰化,以及4)α-甲酰基烯基磺酰亚胺亚胺的烯丙基化。磺胺基亚胺取代的1,7,10和1,7,12-三烯经Ru催化的RCM反应立体选择性地获得了相应的9、10和11元MRNHs,收率很高。在亚磺酰亚胺取代的1,7,10-三烯及其相应的1,10-二烯的情况下,发现在反应性上有一个有趣的差异。尽管三烯容易进行RCM反应,但二烯仅在Ti(O i P
Acid Catalyzed Alcoholysis of Sulfinamides: Unusual Stereochemistry, Kinetics and a Question of Mechanism Involving Sulfurane Intermediates and Their Pseudorotation
formed in this reaction with a full or predominant inversion of configuration at chiral sulfur or with predominant retention of configuration. The steric course of the reaction depends mainly on the size of the dialkylamido group in the sulfinamides and of the alcohols used as nucleophilic reagents. It has been found that bulky reaction components preferentially form sulfinates with retention of configuration
thyl)sulfoximines and carbonyl compounds by an addition-elimination-isomerization reaction sequence. Under basic conditions, complete isomerization of the vinylic sulfoximines, obtained as intermediates, to the corresponding allylicsulfoximines takes place. Chromatographically separable mixtures of (E) and (Z) allylicsulfoximines were isolated in the case of beta,gamma-disubstituted allylic sulfoximines
Spiro- and Bicycloannulation of Sulfoximine-Substituted 2-Hydroxy-dihydropyrans: Enantioselective Synthesis of Spiroketals, Spiroethers, and Oxabicycles and Structure of Dihydropyran Oxocarbenium Ions
skeletons. These routes were extended to the synthesis of spiroketals and spiroethers incorporating additional annulated six-membered rings. Diastereoselective Prinscyclization of mono- and bicyclic 2-alkenyl-2-hydroxy-dihydropyrans was highly selective and afforded chloro-substituted spirocycles. Substituted 2-hydroxy-dihydropyrans were obtained through cyclization of δ-hydroxy ketones, which were synthesized
atom. CCR of axially chiral alkenyl sulfoximines with Ni(PPh3)2Cl2 as a precatalyst and ZnPh2 does not require salt promotion and is stereoretentive. The reaction with Zn(CH2SiMe3)2, however, demands salt promotion and is not stereoretentive. CCR of axially chiralα‐methylated alkenyl sulfoximines afforded persubstituted axially chiralalkenes with high selectivity. Alkenyl (N‐triflyl)sulfoximines