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Chiral 2‐amino‐butanols ( 4 and 5 ) were obtained via the isolation of diastereomeric salt. Then, chiral compounds ( 6 – 9) were synthesized by a sequential procedure involving condensation of chiral 2‐amino‐butanol with ketone and dichloroacetyl chloride. All the compounds were characterized by IR, 1H NMR, 13C NMR, and element analysis. The absolute configurations of ( S )‐ 8 was determined by X‐ray crystallography. 相似文献
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The first synthetic approach to (±)‐Δ3‐2‐hydroxybakuchiol (=4‐[(1E,5E)‐3‐ethenyl‐7‐hydroxy‐3,7‐dimethylocta‐1,5‐dien‐1‐yl]phenol; 14 ) and its analogues 13a – 13f was developed by 12 steps (Schemes 2 and 3). The key features of the approach are the construction of the quaternary C‐center bearing the ethenyl group by a Johnson–Claisen rearrangement (→ 6 ); and of an (E)‐alkenyl iodide via a Takai–Utimoto reaction (→ 11 ); and an arylation via a Negishi cross‐coupling reaction (→ 12e – 12f ). 相似文献
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A series of novel racemic 2‐(1,3‐diaryl‐3‐hydroxypropyl)cyclohexan‐1‐ol derivatives were synthesized from 1,5‐diketones. All the synthesized compounds were characterized by spectroscopic methods. The antibacterial activities of obtained chiral 1,5‐diols were investigated against four Gram‐positive and three Gram‐negative bacteria by determining of minimum inhibitory concentrations (MICs) in vitro. Compounds 3b , 3c , and 3d were found to be active against Enterococcus faecalis and Escherichia coli. In addition, compound 3j were found to be moderately active against all tested bacterial strains. 相似文献
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Alaa A. Hassan Nasr K. Mohamed Lamiaa E. Abd El‐Haleem Stefan Bräse Martin Nieger 《Journal of heterocyclic chemistry》2015,52(5):1368-1372
A series of (Z)‐methyl‐2‐[(Z)‐3‐substituted‐4‐oxo‐2‐(2‐picolinoyl‐/thiophene‐2‐carbonyl)‐hydrazonothiazolidin‐5‐ylidene]acetates were synthesized by condensation N‐substituted‐(2‐picolinoyl‐, thiophene‐2‐carbonyl)hydrazinecarbothioamides with dimethylacetylenedicarboxylate. The structure of thiazolidin‐4‐one derivatives has been confirmed unambiguously by single crystal X‐ray crystallography. 相似文献
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Hao Xu Hua Tian Liangyu Zheng Qingwen Liu Li Wang Suoqin Zhang 《Journal of heterocyclic chemistry》2012,49(5):1108-1113
A series of novel chiral 1‐benzoyl‐2‐(α‐N‐substituted aminoethyl)benzimidazoles are synthesized with the improved method in high yields (72–84%) and developed as nonenzymatic acylating agents for kinetic resolution of racemic α‐amino esters. The process exhibits high enantioselectivity (ee up to 94%) for α‐amino esters under mild reaction conditions. 相似文献
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Novel synthesis of P‐chiral 1,3‐oxaphospholane starting from optically pure propylene oxide is described. The exact structure is confirmed by X‐ray crystallographic analysis. 相似文献
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Agnese Abate Elisabetta Brenna Giovanni Fronza Claudio Fuganti Sabrina Ronzani Stefano Serra 《Helvetica chimica acta》2003,86(3):592-606
The enantiomerically enriched diastereoisomers of the chiral 1,3‐dioxane odorants Floropal® ( 1 ) and Magnolan® ( 2 ) were prepared by an enzyme‐mediated approach. Their olfactory properties were evaluated to investigate differences in the odor perception for the stereoisomers. 相似文献
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(R)‐2,3‐Cyclohexylideneglyceraldehyde,a Chiral Pool Synthon for the Synthesis of 2‐Azido‐1,3‐diols 下载免费PDF全文
Abdul Rouf Mushtaq A. Aga Brijesh Kumar Subhash C. Taneja 《Helvetica chimica acta》2015,98(6):823-833
A new approach was proposed for the synthesis of 2‐azido‐1,3‐diols from easily available and inexpensive chiral pool synthon (R)‐2,3‐O‐cyclohexylidene‐D ‐glyceraldehyde, through Mitsunobu azidation of 1,2‐diols. Both C(2) and C(1) azides in variable ratios were obtained in alkyl substituted diols with C(2) as the major one. 相似文献
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A new series of 1,3‐Benzoxazines were synthesized from ketimines and triphosgene. The synthesized compounds were characterized by IR, 1HNMR, and mass spectral data. The synthesized compounds on bioevaluation indicated significant antifungal activity. 相似文献
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Ravi K. Ujjinamatada Raju S. Appala Yankanagouda S. Agasimundin 《Journal of heterocyclic chemistry》2006,43(2):437-441
New benzofuranyl‐1,3‐benzoxazines and 1,3‐benzoxazin‐2‐ones are synthesized in which benzofuran is coupled with 1,3‐benzoxazines and 1,3‐benzoxazin‐2‐ones through ‐CONH‐ and ‐COCH2‐ bridges, respectively. The antimicrobial activity of these compounds is reported. 相似文献
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Synthesis of New Bis‐1,2,4‐Oxadiazoline Derivatives via 1,3‐Dipolar Cycloaddition Reaction 下载免费PDF全文
A series of novel bis‐oxadiazoline derivatives 4 was synthesized via 1,3‐dipolar cycloaddition reaction of bis‐aldimines 3 , and nitrile oxides generated in situ from various benzohydroximinoyl chlorides in the presence of Et3N. The target products were confirmed by IR, 1H‐NMR, and mass spectrometry. 相似文献
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Madison J. Sowden Jas S. Ward Michael S. Sherburn 《Angewandte Chemie (International ed. in English)》2020,59(10):4145-4153
The first general preparative access to compounds of the 2,3‐diethynyl‐1,3‐butadiene (DEBD) class is reported. The synthesis involves a one‐pot, twofold Sonogashira‐type, Pd0‐catalyzed coupling of two terminal alkynes and a carbonate derivative of a 2‐butyne‐1,4‐diol. The synthesis is broad in scope and members of this structural family are kinetically stable enough to be handled using standard laboratory techniques at ambient temperature. They decompose primarily through heat‐promoted cyclodimerizations, which are impeded by alkyl substitution and accelerated by aryl or alkenyl substitution. An iterative sequence of these unprecedented Sonogashira‐type couplings generates a new type of expanded dendralene. A suitably substituted DEBD carrying two terminal alkyne groups undergoes Glaser–Eglinton cyclo‐oligomerization to produce a new class of expanded radialenes, which are chiral due to restricted rotation about their 1,3‐butadiene units. The structural features giving rise to atropisomerism in these compounds are distinct from those reported previously. 相似文献
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Alicyclic N‐substituted 1,3‐amino alcohols 13‐18 were prepared in a facile way in a one‐pot procedure from 1,3‐oxazines 5‐8 in the presence of a ketone 9‐12 . The complex reaction involves palladium‐catalyzed reduction, debenzylation and/or transimination and further reduction. 相似文献
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Jean‐Franois Carpentier 《Macromolecular rapid communications》2010,31(19):1696-1705
Poly(β‐hydroxyalkanoate)s (PHAs) are a class of aliphatic polyesters that can be efficiently synthesized by ring‐opening polymerization (ROP) of β‐lactones. The case of chiral racemic β‐substituted β‐lactones is particularly appealing since these monomers open the way to original tacticities and materials different from those biotechnologically produced. In this overview, after briefly surveying general considerations associated to the ROP of β‐lactones and metal‐based catalysts used in stereoselective ROP of racemic β‐butyrolactone, special emphasis is given to discrete rare earth catalysts that have allowed the preparation of highly syndiotactic poly(3‐hydroxybutyrate)s. Recent developments – such as preparation of stereocontrolled PHAs with pendant structural groups via (co)polymerization of functional β‐substituted β‐lactones, and highly alternating copolymers obtained by ROP of mixtures of enantiomerically pure but different monomers – are also discussed.
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Suhail Bahu Steven A. Fleming Brad Nilsson Tim Turner 《Journal of heterocyclic chemistry》2001,38(6):1341-1344
Irradiation of an aryl group with a silyl tethered alkene yields a tetracyclic 2‐silaoxane with high regiose‐lectivity. The multicyclic structure has been further modified to give an unstable tricyclic diol. Photocycloaddition between cyclopentene and phenylcyclopropane gave a single major cycloadduct without cyclopropyl ring opening, indicating that the putative radical intermediate involved in cycloaddition apparently has a very short lifetime if it exists at all. 相似文献
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Chiral Phosphoric Acid Catalyzed Asymmetric Synthesis of Hetero‐triarylmethanes from Racemic Indolyl Alcohols 下载免费PDF全文
Caizhen Yue Fei Na Xiantao Fang Yang Cao Prof. Dr. Jon C. Antilla 《Angewandte Chemie (International ed. in English)》2018,57(34):11004-11008
The direct enantioselective 1,4‐ and 1,8‐arylations of 7‐methide‐7H‐indoles and 6‐methide‐6H‐indoles, respectively, generated in situ from diarylmethanols, with electron‐rich arenes as nucleophiles, has been achieved in the presence of chiral phosphoric acids (CPAs). These two remote activation protocols provide an efficient approach for the construction of diverse hetero‐triarylmethanes in high yields (up to 97 %) and with excellent enantioselectivities (up to 96 %). Mechanistically inspired experiments tentatively indicate that the catalytic enantioselective 1,4‐addition as well as the formal SN1 substitution could proceed efficiently in the similar catalytic systems. Furthermore, the modification of the catalytic system and diarylmethanol structure successfully deviates the reactivity toward a remote, highly enantioselective 1,8‐arylation reaction. This flexible activation mode and novel reactivity of diarylmethanols expand the synthetic potential of chiral phosphoric acids. 相似文献
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Asymmetric Synthesis of 1,3‐Butadienyl‐2‐carbinols by the Homoallenylboration of Aldehydes with a Chiral Phosphoric Acid Catalyst 下载免费PDF全文
Prof. Dr. Yiyong Huang Xing Yang Zongchao Lv Chen Cai Cheng Kai Prof. Dr. Yong Pei Dr. Yu Feng 《Angewandte Chemie (International ed. in English)》2015,54(25):7299-7302
Asymmetric C(sp)? C(sp2) bond formation to give enantiomerically enriched 1,3‐butadienyl‐2‐carbinols occurred through a homoallenylboration reaction between a 2,3‐dienylboronic ester and aldehydes under the catalysis of a chiral phosphoric acid (CPA). A diverse range of enantiomerically enriched butadiene‐substituted secondary alcohols with aryl, heterocyclic, and aliphatic substituents were synthesized in very high yield with high enantioselectivity. Preliminary density functional theory (DFT) calculations suggest that the reaction proceeds via a cyclic six‐membered chairlike transition state with essential hydrogen‐bond activation in the allene reagent. The catalytic reaction was amenable to the gram‐scale synthesis of a chiral alkyl butadienyl adduct, which was converted into an interesting optically pure compound bearing a benzo‐fused spirocyclic cyclopentenone framework. 相似文献