手性胍催化酮与1,4-二噻烷-2,5-二醇的串联反应

合成了三种轴手性多氢键胍催化剂,并将其用于催化α,β-不饱和酮和1,4-二噻烷-2,5-二醇的不对称Sulfa-Michael/Aldol串联反应。研究表明:在室温(25℃)时,2mL THF作为溶剂,轴手性胍(1c)作为催化剂,催化剂1c用量为10mol%,能较好地串联该反应,并以较好的收率(75～88%)和较高的对映选择性(80～89%ee)以及较好的非对映选择性(94∶6 dr)获得了目标产物。     

钯催化的1,4-环己二烯的立体选择性1,3-双芳基化反应

基于金属迁移的策略,发展了钯催化的1,4-环己二烯的1,3-双芳基化反应,得到单一的非对映选择性的双芳基化的产物.此反应具有优秀的区域选择性和单一的非对映选择性.实验结果表明在钯迁移的过程中烯烃并没有从钯上解离下来.这一研究为cis-1,3-双芳基取代的环己烷类化合物的合成提供了简便的方法.     

非对映选择性可调的甘氨酸酯与亚胺的高对映选择性Mannich反应

光学活性α,β-二氨基酸是一类重要的合成中间体, 也是许多具有各种生理活性化合物的重要结构片段. 甘氨酸酯衍生物和亚胺的Mannich反应是合成这类化合物的有效方法之一, 至今已有多种手性金属催化剂和有机催化剂应用于这一反应, 但能够同时实现非对映选择性和对映选择性控制的报道很有限. 中国科学院上海有机化学研究所 侯雪龙小组与香港科技大学吴云东教授利用手性二茂铁配体实现了反应的高非对映选择性和对映选择性, 同时通过密度泛函(DFT)计算对反应过程予以研究, 根据计算结果对配体结构进行了优化, 利用配体的电子效应不同, 实现了反应的非对映选择性调控, 以优秀的非对映选择性和对映选择性分别得到syn-或者anti-α,β-二氨基酸衍生物. 这一结果不仅提供了一个高非对映选择性和对映选择性合成syn-或者anti-α,β-二氨基酸衍生物的方法, 也提供了一个反应选择性控制的新途径.     

硝酮1,3-偶极环加成对映选择性配合物催化剂的研究进展

近几年来，1，3-偶极环加成的对映选择性金属配合物催化反应得到了较多研究。人们研制出了一系列控制反应立体选择性的金属配合物催化剂，尤其是对硝酮和链烯烃反应，许多催化剂对Dies-Alder反应和1，3-偶极环加成反应同时具有较高的对映及非对映选择性。     

基于化学和对映选择性转移氢化的β,γ-炔基α-氨基酸酯的催化不对称合成研究（英文）

报道了一个通过β,γ-炔基α-亚胺酸酯的化学和对映选择性转移氢化反应来合成光学纯β,γ-炔基α-氨基酸酯的方法.该不对称还原反应所展示出的优秀的化学选择性是由手性磷酸作为催化剂以及苯并噻唑啉作为氢负供体实现的.反应展示出了良好的官能团兼容性,高对映选择性地合成了一系列光学活性的非天然氨基酸酯化合物.     

基于α-溴代酮的催化不对称合成3,3-螺环丙基吲哚酮和乙烯基环丙烷

在甲基化奎尼丁(20mol%)的催化下,分别实现了α-溴代酮与3-(取代亚甲基)吲哚酮和缺电子1,3-二烯的高度非对映选择性和对映选择性的环丙烷化反应,以46%~99%收率、高达98%ee和20∶1 dr生成相应的3,3-螺环丙基吲哚酮和乙烯基环丙烷.通过催化的氮叶立德策略,成功发展了一种用于上述手性化合物的简便合成方法.     

邻羟基苄醇与邻羟基苯乙烯的催化不对称[4+2]环加成反应——手性色满骨架的立体选择性构建

研究了手性磷酸催化下邻羟基苄醇和邻羟基苯乙烯的不对称［4+2］环加成反应,立体选择性地一步构建了手性2,4-二取代四氢色满骨架,该反应具有较高的收率、中等到较高的对映选择性和很好的非对映选择性（最高产率为78%,最高ee值为72%,dr值基本都大于95∶5）.带有不同取代基的多种邻羟基苄醇和邻羟基苯乙烯均适用于该反应,电子效应对于该反应的对映选择性有一定影响,其中连有供电子基的底物具有更高的反应活性和对映选择性.由邻羟基苄醇原位生成的邻亚甲基苯醌中间体和邻羟基苯乙烯可以同时与催化剂手性磷酸形成双重氢键,对于促进反应的进行和控制该反应的对映选择性起着至关重要的作用.     

烯丙型醇与取代肼的对映专一性烯丙型烷基化反应

发展了首例烯丙型醇与取代肼的对映专一性烯丙型烷基化反应.在钯/外消旋2,2'-双(二苯膦基)-1,1'-联萘(BINAP)/硼酸的催化下,一系列高度对映富集的烯丙型醇与取代肼于室温进行烯丙型烷基化反应,具有高度的区域选择性,立体构型的保留率大于95%,适于合成高对映纯度的烯丙型肼.另外,该反应的唯一副产物是水,对环境友好.     

亚甲胺叶立德参与的不对称1,3-偶极环加成构建含连续季碳中心的螺四氢吡咯衍生物

Cu(I)催化的亚甲胺叶立德和亚环丙基乙酸乙酯参与的不对称endo-1,3-偶极环加成反应,高效构建了多官能化、含有多个连续季碳中心的5-氮杂-[2,4]庚烷化合物.此反应具有广泛的底物适用性,α-取代的和α-非取代的亚甲胺叶立德和亚环丙基乙酸乙酯都能很好的参与反应,并以很高的产率、优秀的非对映选择性(95:5–98:2 d.r)和对映选择性(87%–98%ee)生成相应的在2,3,4位上含有连续季碳中心的螺四氢吡咯化合物.     

以2-氨基-2''-羟基-1,1''-联萘为骨架的有机小分子催化的直接羟醛缩合反应的研究

研究了2-氨基-2'-羟基-1,1'-联萘衍生的有机小分子催化剂催化的直接羟醛缩合反应.以丙酮为反应物时最好,得到了99%的收率.以环酮为底物时,最高得到99:1的非对映选择性,89%的对映选择性.     

A stereo-divergent route to aminocyclopentitol derivatives

A stereo-divergent synthetic strategy based on diastereoselective vinylation of an α-amino aldehyde, ring-closing metathesis reaction and diastereoselective dihydroxylation reaction as key steps has been developed for the synthesis of three aminocyclopentitol derivatives of chemical and biological relevance.     

Diastereoselective synthesis of (2S,5R)-5-hydroxypipecolic acid and 6-substituted derivatives

[reaction: see text] Herein, we report a diastereoselective synthesis of the natural product (2S,5R)-5-hydroxypipecolic acid and 6-substituted derivatives thereof. The key step in the synthetic sequence is a novel highly diastereoselective epoxidation reaction of an enantiomerically pure cyclic enamide intermediate.     

Remarkable change of the diastereoselection in the dye-sensitized ene hydroperoxidation of chiral alkenes by zeolite confinement

[reaction: see text] The ene reaction of singlet oxygen with chiral trisubstituted alkenes bearing an alkyl and a phenyl group at the stereogenic center is erythro diastereoselective in solution and threo diastereoselective if carried out within zeolite Na-Y. The change of the diastereoselection trend by zeolite confinement is attributed to a synergism of steric effects and cation-pi interactions.     

Utilization of 1-oxa-2,2-(dimesityl)silacyclopentane acetals in the stereoselective synthesis of polyols

We have developed a route for the stereoselective synthesis of 1-oxa-2,2-(dimesityl)silacyclopentane acetals, intermediates in the synthesis of highly functionalized 1,3-diols. This route involves a diastereoselective conjugate addition reaction of a hydrosilyl anion, a subsequent diastereoselective enolate alkylation, and a fluoride-catalyzed intramolecular hydrosilylation reaction to afford the oxasilacyclopentane acetal. A highly selective nucleophilic substitution reaction, followed by oxidation of the C-Si bond, leads to the desired polyol.     

Diastereoselective cationic tandem cyclizations to N-heterocyclic scaffolds: total synthesis of (-)-dysibetaine PP

[reaction: see text] Herein, we report a short and diastereoselective synthesis of the natural product (-)-dysibetaine PP. The key step in the synthetic sequence is a novel highly diastereoselective tandem-cyclization reaction of an enantiomerically pure dipeptide. This cyclization methodology is applied in the synthesis of a broader range of N-heterocyclic scaffolds.     

A highly enantio- and diastereoselective catalytic intramolecular Stetter reaction

A highly enantio- and diastereoselective intramolecular Stetter reaction has been developed. Subjection of alpha,alpha-disubstituted Michael acceptors to an asymmetric intramolecular Stetter reaction results in a highly enantioselective conjugate addition and a diastereoselective proton transfer. Available evidence suggests the diastereoselective protonation occurs via intramolecular delivery to the sterically more hindered face of the enolate. The scope of the trisubstituted Michael acceptors has been examined and found to be broad with respect to the size of the alpha-substituent and nature of the Michael acceptor. Aliphatic and aromatic aldehydes were examined and found to afford the desired product in good overall yield with high enantio- and diastereoselectivity.     

Multi-component regio- and diastereoselective cobalt-catalyzed hydrovinylation/allylboration reaction sequence

The combination of a regioselective cobalt-catalyzed 1,4-hydrovinylation and the diastereoselective allylboronation reaction leads to a wide scope of functionalized hydroxydienyl esters in a one-pot reaction in excellent yields. With catalytic amounts of base, these products are easily converted either into α,β,γ,δ-unsaturated hydroxyl esters or complex tetrasubstituted tetrahydropyrans in chemo- and diastereoselective fashions. In addition, a high-yielding four-component one-pot reaction involving an acrylate, two different and unsymmetrical 1,3-dienes, and an unsaturated aldehyde is presented.     

High chelation control of three contiguous stereogenic centers in the Reformatsky reactions of indium enolates with alpha-hydroxy ketones: unexpected stereochemistry of lactone formation

[reaction: see text] A boat-type of chelated bicyclic transition state involving highly diastereoselective construction of three contiguous stereogenic centers in the Reformatsky reaction of indium enolates with alpha-alkoxy/hydroxy ketones is proposed. alpha-Hydroxy ketones with indium enolates furnished highly diastereoselective lactones, while alpha-alkoxy ketones gave acyclic esters in moderate selectivities. X-ray structure analyses of key products unequivocally revealed the unexpected stereochemistry of products and the reaction pathway.     

Diastereoselective synthesis of the Leu-Pro type phosphinyl dipeptide isostere

A diastereoselective synthesis of the Leu-Pro type phosphinyl dipeptide isostere in its protected form was achieved from stereodefined α-amino-H-phosphinate. The methodology involved a cross-coupling reaction with alkenyl triflate and subsequent diastereoselective hydrogenation of the alkene moiety, which capitalized on the phosphorus chirality.     

First total synthesis of antimitotic compound, (+)-phomopsidin

[reaction: see text] The first total synthesis of (+)-phomopsidin has been achieved via a diastereoselective transannular Diels-Alder (TADA) reaction. Key steps in the synthesis include diastereoselective ynone reduction with (-)-alpha-pinene and 9-BBN, macrocyclization by E-selective intramolecular Horner-Wadsworth-Emmons (HWE) reaction, as well as carbometalation under Wipf's conditions, followed by HWE reaction at low temperature to selectively construct the (E)-1-methylpropenyl and (1E,2E)-4-carboxy-1,3-butadienyl substituents.