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手性全碳季碳立体中心的高效构建一直是不对称催化领域的难点和热点.其中,α-全碳季碳非环状醛因具有立体环境拥挤和构象多变性等结构特点,相关不对称合成方法一直发展缓慢.本工作基于手性醛和高烯丙基醇化合物的合成应用重要性,通过Antilla烯丙基化反应,采用2,4,6-三异丙基苯基取代的联萘二酚型手性磷酸催化剂,以较好的产率、立体选择性和选择性系数(最高达到37.0),实现了外消旋α-全碳季碳非环状醛的动力学拆分,为含α-全碳季碳的醛和高烯丙基醇两类手性化合物的合成提供了新思路. 相似文献
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过渡金属催化烯烃的不对称双碳官能团化反应提供了一种快速构建手性化合物的简便方法,近年来备受化学研究者们的关注[1].目前主要的研究思路是通过设计含苯环的底物现场生成芳基金属物种,来进行不活泼烯烃的分子内不对称双官能团化反应.对于含有非苯并底物的非活化烯烃的不对称双碳官能团化反应来实现季碳手性中心的构建,已报道的仅有少数通过酰基金属中间体的策略[2-4].2010年,Takemoto等[2]报道了一例钯催化烯烃和胺甲酰氰的不对称胺酰基氰化反应来构建季碳手性中心。 相似文献
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在有机合成中,季碳中心的构建始终是一项充满挑战的课题.含手性季碳中心的胺基膦酸化合物以其多样的生物活性,如酶抑制剂、抗真菌剂、抗菌剂和抗病毒剂等,受到了科研工作者的广泛关注.目前已有许多合成策略报道,其中亲核试剂与α-酮亚胺膦酸酯的不对称加成策略为含手性季碳中心胺基膦酸衍生物的合成提供了一条简洁有效的路径,但是却鲜有报道,已有的报道也仅局限于乙酰氰、丙酮、硝基甲烷和芳基硼酸作亲核试剂.为满足多样的手性胺基膦酸衍生物的合成需求,新的合成策略和亲核源仍有待进一步发展.值得一提的是,不对称傅-克反应是一种非常有效的构建碳-碳键的合成方法,并已有广泛报道.基于吲哚与亚胺底物的傅-克反应经验,我们研究组发展了一种有机催化吲哚与环状酮亚胺膦酸酯傅-克反应合成含手性季碳胺基膦酸衍生物的方法,使用的有机催化剂是手性磷酸.通过对溶剂、催化剂和温度的筛选发现,使用在3,3′-位引入吸电子的3,5-二三氟甲基苯基取代的H8-BINOL衍生的手性磷酸作催化剂,反应温度为30 oC,溶剂为均三甲苯时,最高能以98%对映选择性得到含手性季碳胺基膦酸酯化合物.该反应操作简单,条件温和,不仅适用于吲哚衍生物,对吡咯也能取得较好结果.总之,该方法提供了一条简洁有效的合成手性胺基膦酸衍生物的途径. 相似文献
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运用不含手性碳的非对称化合物S-BNP酸(S-phosphorsaeure-(1,1'-binaphthyl-2,2'-diylester))作反应试剂用快原子轰击反应质谱法(FAB-RMS)测定手性化合物的绝对构型.发现非对称手性化合物可与不对称手性化合物在质谱中发生立体选择性反应,S-BNP酸可作为一种新的反应试剂来测定手性化合物的绝对构型. 相似文献
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脯氨酸催化的不对称有机反应 总被引:1,自引:0,他引:1
脯氨酸作为一种结构简单、商品化的、廉价小分子手性催化剂,在多种不对称催化反应中表现出非常好的催化性能,本文综述了近年来脯氨酸直接催化的不对称有机反应涉及Aldol反应,Mannich反应,Michael反应,Diels-Alder反应,直接α-胺化反应,α-氧胺化反应,Baylis-Hillman反应,还原反应和氧化反应的进展并展望了其应用前景。 相似文献
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(R)-螺[4,5]癸-2,7-二酮的合成 总被引:3,自引:1,他引:3
从环己烯酮出发,经手性催化的Michael加成反应,Wolff重排反应延长碳链, 再利用重氮化合物的C-H插入反应,以8步反应28.5%的总收率合成了手性β,β '-螺二酮.在合成路线中手性中心的构型保持不变.在最后的检测中未发现另一对 映体,开始产生的手性中心在合成过程没有消旋化。 相似文献
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1,3-diaryl propanones (1a-6a) and 1,3-diaryl-2-carbomethoxy-propanones (1b-6b) have been synthesized through facile palladium catalysed arylation of Baylis- Hillman adducts. 相似文献
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[reaction: see text] Readily available ferrocenyldialkylphosphines are effective air-stable catalysts for Baylis-Hillman reaction between aldehydes and acrylates, affording the corresponding adducts in high yields and short reaction times. A set of readily accessible planar chiral ferrocenyldialkylphosphines have been tested in asymmetric Baylis-Hillman reactions. The best enantioselectivities were obtained using Mandyphos as chiral catalyst (up to 65% ee). 相似文献
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《Tetrahedron: Asymmetry》2005,16(7):1385-1391
In the aza-Baylis–Hillman reaction of N-sulfonated imines with 2-cyclohexen-1-one or 2-cyclopenten-1-one, we found that by using (R)-2′-dimethylphosphanyl-[1,1′]binaphthalenyl-2-ol LB1 as a chiral phosphine Lewis base, the corresponding Baylis–Hillman adducts 2 or 3 can be obtained in good yields and moderate enantiomeric excess. The structure of this chiral phosphine Lewis base on chiral induction in this reaction has also been discussed. 相似文献
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8-Phenylmenthol 1 is used as a chiral auxiliary in the Baylis-Hillman reaction using a range of aldehydes as substrate. Best results (70% d. e.) are obtained when the reaction is rapid, as is the case with trichloroacetaldehyde. 相似文献
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The saccharide‐based chiral bifunctional thiourea‐phosphines were developed as chiral organocatalysts for the intramolecular Morita‐Baylis‐Hillman reaction of ω‐formyl‐enones. With only 2 mol% of thiourea‐phosphine catalyst 3c , chiral functionalized cyclohexenes were achieved under mild reaction conditions with excellent yields and enantioselectivities. 相似文献
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Shunsuke Kotani Masaya Ito Hirono Nozaki Masaharu Sugiura Masamichi Ogasawara Makoto Nakajima 《Tetrahedron letters》2013
An application of a hypervalent silicon complex, generated from a chiral phosphine oxide catalyst and silicon tetrachloride, to the enantioselective organocatalytic Morita–Baylis–Hillman reaction is described. A chloride anion liberated from the hypervalent silicon complex smoothly generated a γ-chloro silyl enol ether that subsequently reacted with an aldehyde to afford the Baylis–Hillman adducts in good yields and with good enantioselectivities. 相似文献
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《Tetrahedron: Asymmetry》2007,18(16):1990-1994
Planar chiral [2,2]cyclophane monophosphines are efficient catalyst in the reaction of Morita–Baylis–Hillman adducts with phthalimide. The corresponding allylic substituted products were afforded in high yields and in good to moderate ee. 相似文献
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The strategy of double asymmetric induction was utilized in Baylis-Hillman reaction for the first time by the coupling of chiral aldehydes with chiral acrylate (1,2:5,6-di-O-isopropylidene-alpha-D-glucofuranose-3-acrylate) to obtain corresponding adducts with high syn diastereoselectivities (de >90%) in moderate to good yields. 相似文献
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The coupling of electrophiles with activated alkenes by using tertiary amines or phosphines is generally known as the Baylis–Hillman reaction. It is a useful and atom‐economical carbon–carbon bond‐forming reaction that generates multifunctionalized products. This reaction is notoriously slow; yields are often low and substrate‐dependent. The asymmetric reaction is still limited especially for unactivated olefins such as acrylates. Imidazolines have been developed as ligands in metal‐catalyzed reactions and have also been used as privileged structures in diversity‐oriented synthesis. A series of novel chiral imidazolines were prepared and used to develop asymmetric Baylis–Hillman reactions. These imidazolines promote the reactions of various aromatic aldehydes with unactivated acrylates. Enantiomeric excesses of up to 60 % and high yields were obtained by using stoichiometric amounts of the promoter. Furthermore, the imidazolines are also suitable promoters for the reactions between aromatic aldehydes and alkyl vinyl ketones. Enantiomeric excesses of up to 78 % and high yields were obtained with 50 mol % of an imidazoline with a chiral methylnaphthyl group. These chiral imidazolines are easily prepared from commercially available amino alcohols and can be easily recovered for reuse without loss of product enantioselectivity. 相似文献
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Chiral Lewis acid-catalyzed asymmetric Baylis-Hillman reactions 总被引:1,自引:0,他引:1
An effective chiral Lewis acid-catalyzed asymmetric Baylis-Hillman reaction is described. Good to high enantioselectivities were obtained using 3 mol % chiral catalyst. Novel camphor-derived dimerized ligands were prepared from the condensation of (+)-ketopinic acid with the corresponding diamines and hydrazine under acidic conditions. When alpha-naphthyl acrylate was used as a Michael acceptor, the reaction is complete within 20 min with high stereoselectivity and in reasonable chemical yields. 相似文献