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1.
Stereoselective Metal‐Free Synthesis of β‐Amino Thioesters with Tertiary and Quaternary Stereogenic Centers
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Dr. Annette Bahlinger Dr. Sven P. Fritz Prof. Helma Wennemers 《Angewandte Chemie (International ed. in English)》2014,53(33):8779-8783
β‐Amino thioesters are important natural building blocks for the synthesis of numerous bioactive molecules. An organocatalyzed Mannich reaction was developed which provides direct and highly stereoselective access to acyclic β2‐ and β2,3,3‐amino thioesters with adjacent tertiary and quaternary stereocenters. Mechanistic studies showed that the stereochemical course of the reaction can be controlled by the choice of the substrates. The β‐amino thioesters were further functionalized by, for example, stereoselective decarboxylation to access β2,3‐frameworks. In addition, the value of the β‐amino thioesters was shown in coupling‐reagent‐free peptide synthesis. 相似文献
2.
Kurella Sreenivasulu Pramod S. Chaudhari Srinivas Achanta Abhishek Sud Vilas Dahanukar Christopher J. Cobley Fiona Llewellyn‐Beard Rakeshwar Bandichhor 《化学:亚洲杂志》2020,15(10):1605-1608
An alternate formal synthesis of Sitagliptin phosphate is disclosed from 2,4,5‐trifluorobenzadehyde in 8 linear steps with an overall yield of 31%. The chiral β‐amino acid moiety present in sitaglitpin is installed via an asymmetric hydrogenation followed by a stereoselective Hofmann rearrangement as the key steps. The key chiral intermediate Boc‐amino acid 1 prepared by this novel route was further converted to Sitagliptin phosphate following the known literature protocol. 相似文献
3.
Practical Synthesis of anti‐β‐Hydroxy‐α‐Amino Acids by PdII‐Catalyzed Sequential C(sp3)H Functionalization
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Kai Chen Shuo‐Qing Zhang Huai‐Zhi Jiang Jing‐Wen Xu Prof. Dr. Bing‐Feng Shi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(8):3264-3270
An improved and practical procedure for the stereoselective synthesis of anti‐β‐hydroxy‐α‐amino acids (anti‐βhAAs), by palladium‐catalyzed sequential C(sp3)?H functionalization directed by 8‐aminoquinoline auxiliary, is described. followed by a previously established monoarylation and/or alkylation of the β‐methyl C(sp3)?H of alanine derivative, β‐acetoxylation of both alkylic and benzylic methylene C(sp3)?H bonds affords various anti‐β‐hydroxy‐α‐amino acid derivatives. As an example, the synthesis of β‐mercapto‐α‐amino acids, which are highly important to the extension of native chemical ligation chemistry beyond cysteine, is described. The synthetic potential of this protocol is further demonstrated by the synthesis of diverse β‐branched α‐amino acids. The observed diastereoselectivities are strongly influenced by electronic effects of aromatic AAs and steric effects of the linear side‐chain AAs, which could be explained by the competition of intramolecular C?OAc bond reductive elimination from PdIV intermediates vs. intermolecular attack by an external nucleophile (AcO?) in an SN2‐type process. 相似文献
4.
Sinceitsdiscovery ,Wittigreactionhasbecomeoneofprimarymethodsfortheformationofcarbon carbondoublebondsandbeenwidelyusedinthesynthesisofnaturalproducts .1,2 Recently ,itwasfoundthatprimaryalcoholscanundergothetandemreactionofoxidation Wittigreactionwithphos… 相似文献
5.
Divergent and Stereoselective Synthesis of β‐Silyl‐α‐Amino Acids through Palladium‐Catalyzed Intermolecular Silylation of Unactivated Primary and Secondary C−H Bonds
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Yue‐Jin Liu Yan‐Hua Liu Zhuo‐Zhuo Zhang Sheng‐Yi Yan Kai Chen Prof. Dr. Bing‐Feng Shi 《Angewandte Chemie (International ed. in English)》2016,55(44):13859-13862
A general and practical PdII‐catalyzed intermolecular silylation of primary and secondary C?H bonds of α‐amino acids and simple aliphatic acids is reported. This method provides divergent and stereoselective access to a variety of optical pure β‐silyl‐α‐amino acids, which are useful for genetic technologies and proteomics. It can also be readily performed on a gram scale and the auxiliary can be easily removed with retention of configuration. The synthetic importance of this method is further demonstrated by the late‐stage functionalization of biological small molecules, such as (?)‐santonin and β‐cholic acid. Moreover, several key palladacycles were successfully isolated and characterized to elucidate the mechanism of this β?C(sp3)‐H silylation process. 相似文献
6.
Markus W. Weishaupt Stefan Matthies Prof. Dr. Peter H. Seeberger 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(37):12497-12503
β‐Glucans are a group of structurally heterogeneous polysaccharides found in bacteria, fungi, algae and plants. β‐(1,3)‐D ‐Glucans have been studied in most detail due to their impact on the immune system of vertebrates. The studies into the immunomodulatory properties of these glucans are typically carried out with isolates that contain a heterogeneous mixture of polysaccharides of different chain lengths and varying degrees of branching. In order to determine the structure–activity relationship of β‐(1,3)‐glucans, access to homogeneous, structurally‐defined samples of these oligosaccharides that are only available through chemical synthesis is required. The syntheses of β‐glucans reported to date rely on the classical solution‐phase approach. We describe the first automated solid‐phase synthesis of a β‐glucan oligosaccharide that was made possible by innovating and optimizing the linker and glycosylating agent combination. A β‐(1,3)‐glucan dodecasaccharide was assembled in 56 h in a stereoselective fashion with an average yield of 88 % per step. This automated approach provides means for the fast and efficient assembly of linker‐functionalized mono‐ to dodecasaccharide β‐(1,3)‐glucans required for biological studies. 相似文献
7.
Min Liu Xing‐Wen Sun Dr. Ming‐Hua Xu Prof. Dr. Guo‐Qiang Lin Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(39):10217-10224
An efficient and convenient α‐hydroxyallylation approach for the asymmetric synthesis of a variety of β‐amino‐α‐vinyl alcohols has been successfully developed. A wide range of vinylic amino alcohol derivatives could be obtained in very good yields and with excellent diastereomeric ratios of up to 99:1 in favor of anti isomers by highly diastereoselective Zn‐promoted benzoyloxyallylation of chiral N‐tert‐butanesulfinyl imines with 3‐bromopropenyl benzoate at room temperature. In particular, excellent enantioinduction of the two new stereogenic centers was observed, with up to 98 % ee. The method provides a new route for the direct α‐hydroxyallylation of imines in a highly stereoselective manner. Moreover, the synthetic value of the method has also been demonstrated by the most concise and straightforward synthesis of (?)‐cytoxazone yet reported. 相似文献
8.
Taoufik Rohand Victor N. Mkpenie Mohammadine El Haddad Istvn E. Mark 《Journal of heterocyclic chemistry》2019,56(2):690-695
A novel one‐pot synthesis of 3‐amino‐1,2,4‐triazole developed via iron (III) catalyzed route is reported. The new method is more efficient, simple, and convenient and presents a concise new strategy for the synthesis of 3‐amino‐1,2,4‐triazole derivatives. The iron (III) complex intermediate assisted in the intramolecular bond cyclization owing to its Lewis acidity or oxidizing properties. A series of aromatic nitriles bearing different electron‐donating and electron‐withdrawing groups substituted at para and/or ortho positions were also investigated. The position of the substituents affected the yield of the final compound, with the para‐substituted substrates giving relatively higher yields. 相似文献
9.
A Versatile Approach to CF3‐Containing 2‐Pyrrolidones by Tandem Michael Addition–Cyclization: Exemplification in the Synthesis of Amidine Class BACE1 Inhibitors
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Dr. Natalia Mateu Myriam Ciordia Dr. Oscar Delgado Dr. María Sánchez‐Roselló Dr. Andrés A. Trabanco Dr. Michiel Van Gool Dr. Gary Tresadern Laura Pérez‐Benito Prof. Dr. Santos Fustero 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(33):11719-11726
The synthesis of new fluorinated pyrrolidones starting from unprotected amino esters and amino nitriles through a Michael addition–lactamization sequence is described. The resulting CF3‐containing building blocks, bearing a quaternary stereogenic center adjacent to the fluorinated group, have been converted into amino pyrrolidines that display potent β‐secretase 1 (BACE1) inhibitory activity. This work constitutes an example of selective fluorination as a valid strategy for the modulation of physicochemical and biological properties of lead compounds in drug discovery. 相似文献
10.
New functional dehydrophenylalanines 3 were prepared from β‐amino alcohols 1 in a two‐step reaction sequence. The synthesis involved chlorination of the starting amino alcohols 1 to afford the intermediate erythro β‐chloroamines 2 . Treatment of the latter with an appropriate base led to a highly stereoselective elimination reaction, giving the corresponding (E)‐dehydrophenylalanine derivatives 3 in high yields. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 23:91–98, 2012; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20756 相似文献
11.
Hai Nguyen Danyang Zhu Xiaohua Li Jianglong Zhu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2016,128(15):4845-4849
A new and efficient approach for direct and stereoselective synthesis of β‐mannopyranosides by anomeric O‐alkylation has been developed. This anomeric O‐alkylation of mannopyranose‐derived lactols is proposed to occur under synergistic control of a kinetic anomeric effect and metal chelation. The presence of a conformationally flexible C6 oxygen atom in the sugar‐derived lactol donors is required for this anomeric O‐alkylation to be efficient, probably because of its chelation with cesium ion. In contrast, the presence of a C2 oxygen atom plays a minor role. This glycosylation method has been successfully utilized for the synthesis of the trisaccharide core of complex N‐linked glycans. 相似文献
12.
Stereocontrolled Synthesis of syn‐β‐Hydroxy‐α‐Amino Acids by Direct Aldolization of Pseudoephenamine Glycinamide
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Dr. Ian B. Seiple Jaron A. M. Mercer Robin J. Sussman Ziyang Zhang Prof. Dr. Andrew G. Myers 《Angewandte Chemie (International ed. in English)》2014,53(18):4642-4647
β‐Hydroxy‐α‐amino acids figure prominently as chiral building blocks in chemical synthesis and serve as precursors to numerous important medicines. Reported herein is a method for the synthesis of β‐hydroxy‐α‐amino acid derivatives by aldolization of pseudoephenamine glycinamide, which can be prepared from pseudoephenamine in a one‐flask protocol. Enolization of (R,R)‐ or (S,S)‐pseudoephenamine glycinamide with lithium hexamethyldisilazide in the presence of LiCl followed by addition of an aldehyde or ketone substrate affords aldol addition products that are stereochemically homologous with L ‐ or D ‐threonine, respectively. These products, which are typically solids, can be obtained in stereoisomerically pure form in yields of 55–98 %, and are readily transformed into β‐hydroxy‐α‐amino acids by mild hydrolysis or into 2‐amino‐1,3‐diols by reduction with sodium borohydride. This new chemistry greatly facilitates the construction of novel antibiotics of several different classes. 相似文献
13.
Biswanath Das Rathod Aravind Kumar Ponnaboina Thirupathi 《Helvetica chimica acta》2007,90(6):1206-1210
A simple and efficient method has been developed for the synthesis of α‐amino nitriles from aldehydes, amines and trimethylsilyl cyanide (Me3SiCN) in the presence of a catalytic amount of cyanuric acid at room temperature. 相似文献
14.
Răzvan C. Cioc Daan J. H. van der Niet Elwin Janssen Dr. Eelco Ruijter Prof. Dr. Romano V. A. Orru 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(21):7808-7813
A practical two‐stage one‐pot synthesis of N‐substituted β‐amino alcohols using aldehydes and isocyanides as starting materials has been developed. This method features mild reaction conditions, broad scope, and general tolerance of functional groups. Based on a less common central carbon–carbon bond disconnection, this protocol complements traditional approaches that involve amines and various carbon electrophiles (epoxides, α‐halo ketones, β‐halohydrins). Medicinally relevant products can be prepared in a concise and efficient way from simple building blocks, as demonstrated in the synthesis of the antiasthma drug salbutamol. Upgrading the synthesis to an enantioselective variant is also feasible. 相似文献
15.
Stereoselective β‐mannosylation has been recognized as one of the greatest challenges of carbohydrate chemistry. Herein, we described a practical method for stereoselective construction of β‐mannosides by using a 2,6‐lactone‐bridged thiomannosyl donor through the remote acyl‐group participation as well as the steric effect of O‐4 substituent. The two effects are enabled through the conversion of a regular mannopyranosyl 4C1 conformation into a 2,6‐lactone bridged conformation. The lactone donor could be readily prepared in three steps on a gram scale and the β‐mannosylation proceeded smoothly with high stereoselectivity for primary, secondary and tertiary alcohol acceptors. In addition, this strategy was successfully applied to the synthesis of a naturally occurring trisaccharide. 相似文献
16.
《Chemical record (New York, N.Y.)》2018,18(3):266-281
Fluorine‐containing organic molecules have generated increasing impact in drug research over the past decade. Their preparation and development of novel synthetic methods towards new types of fluorinated molecules among them of β‐amino acid derivatives has received large interest. Our research group have designed various highly selective and stereocontrolled methods for the construction of fluorine‐containing cyclic β‐amino acid derivatives. The synthetic approaches developed for the synthesis of various pharmacologically interesting cyclic β‐amino acid derivatives as monomers with multiple stereogenic centers might be valuable protocols for the access of other classes of organic compounds. 相似文献
17.
Sulfonamide‐Promoted Palladium(II)‐Catalyzed Alkylation of Unactivated Methylene C(sp3)H Bonds with Alkyl Iodides
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Kai Chen Prof. Dr. Bing‐Feng Shi 《Angewandte Chemie (International ed. in English)》2014,53(44):11950-11954
The alkylation of unactivated β‐methylene C(sp3)? H bonds of α‐amino acid substrates with a broad range of alkyl iodides using Pd(OAc)2 as the catalyst is described. The addition of NaOCN and 4‐Cl‐C6H4SO2NH2 was found to be crucial for the success of this transformation. The reaction is compatible with a diverse array of functional groups and proceeds with high diastereoselectivity. Furthermore, various β,β‐hetero‐dialkyl‐ and β‐alkyl‐β‐aryl‐α‐amino acids were prepared by sequential C(sp3)? H functionalization of an alanine‐derived substrate, thus providing a versatile strategy for the stereoselective synthesis of unnatural β‐disubstituted α‐amino acids. 相似文献
18.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(25):7324-7328
A general and user‐friendly synthesis of β‐lactams is reported that makes use of Pd0‐catalyzed carbamoylation of C(sp3)−H bonds, and operates under stoichiometric carbon monoxide in a two‐chamber reactor. This reaction is compatible with a range of primary, secondary and activated tertiary C−H bonds, in contrast to previous methods based on C(sp3)−H activation. In addition, the feasibility of an enantioselective version using a chiral phosphonite ligand is demonstrated. Finally, this method can be employed to synthesize valuable enantiopure free β‐lactams and β‐amino acids. 相似文献
19.
This report delineates our efforts towards the synthesis of a stereochemically well‐defined ketone, the C1?C10 fragment of muamvatin, the first example of a 2, 4, 6‐trioxaadamantane ring skeletal polypropionate marine natural product, using two non‐aldol variants. i) The Shimizu reaction, a Pd(0) mediated stereoselective epoxy‐ring opening of alkenyl oxiranes, was employed for the stereoselective installation of methyl groups in syn‐fashion and ii) Bode's protocol, a NHC‐mediated reaction on β‐epoxy aldehydes, was utilized for stereoselective construction of methyl and hydroxyl groups in anti‐fashion. 相似文献
20.
Yichu Liu Yibing Wang Wenhao Dai Wei Huang Yingxia Li Hong Liu 《Angewandte Chemie (International ed. in English)》2020,59(9):3491-3494
We have developed a highly efficient and practical approach for palladium‐catalyzed trifluoroacetate‐promoted N‐quinolylcarboxamide‐directed glycosylation of inert β‐C(sp3)?H bonds of N‐phthaloyl α‐amino acids with glycals under mild conditions. For the first time, C(sp3)?H activation for glycosylation was achieved to build C‐alkyl glycosides. This method facilitates the synthesis of various β‐substituted C‐alkyl glycoamino acids and offers a tool for glycopeptide synthesis. 相似文献