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1.
Lipase‐Catalyzed Dynamic Kinetic Resolution of C1‐ and C2‐Symmetric Racemic Axially Chiral 2,2′‐Dihydroxy‐1,1′‐biaryls
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Dr. Gamal A. I. Moustafa Yasuhiro Oki Prof. Dr. Shuji Akai 《Angewandte Chemie (International ed. in English)》2018,57(32):10278-10282
We have discovered that the racemization of configurationally stable, axially chiral 2,2′‐dihydroxy‐1,1′‐biaryls proceeds with a catalytic amount of a cyclopentadienylruthenium(II) complex at 35–50 °C. Combining this racemization procedure with lipase‐catalyzed kinetic resolution led to the first lipase/metal‐integrated dynamic kinetic resolution of racemic axially chiral biaryl compounds. The method was applied to the synthesis of various enantio‐enriched C1‐ and C2‐symmetric biaryl diols in yields of up to 98 % and enantiomeric excesses of up to 98 %, which paves the way for new developments in the field of asymmetric synthesis. 相似文献
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Thomas D. McGrath Mark A. Fox Alan J. Welch 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(4):487-488
The title compound, 9‐iodo‐1,2‐diphenyl‐1,2‐dicarba‐closo‐dodecaborane(9), C14H19B10I, has the expected pseudo‐icosahedral cluster geometry, with a cage C—C distance of 1.724 (4) Å, comparable to that in the non‐iodinated parent. However, the twist angles, θ, of the phenyl rings are 2.1 (6) and 27.6 (5)°, the latter being unusually large. 相似文献
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Formation of Fluorinated Amido Esters through Unexpected C3−C4 Bond Fission in 4‐Trifluoromethyl‐3‐oxo‐β‐lactams
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Hang Dao Thi Dr. Hannelore Goossens Dr. Dietmar Hertsen Valerie Otte Prof. Dr. Tuyen Van Nguyen Prof. Dr. Veronique Van Speybroeck Prof. Dr. Matthias D'hooghe 《化学:亚洲杂志》2018,13(4):421-431
4‐Trifluoromethyl‐3‐oxo‐β‐lactams were unexpectedly transformed into 2‐[(2,2‐difluorovinyl)amino]‐2‐oxoacetates as major products, accompanied by minor amounts of 2‐oxo‐2‐[(2,2,2‐trifluoroethyl)amino]acetates, upon treatment with alkyl halides and triethylamine in DMSO. This peculiar C3?C4 bond fission reactivity was investigated in‐depth, from both an experimental and a computational point of view, in order to shed light on the underlying reaction mechanism. 相似文献
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Giuliana Biagi Irene Giorgi Oreste Livi Federica Pacchini Valerio Scartoni Oreste Leroy Salerni 《Journal of heterocyclic chemistry》2005,42(5):743-749
Title compounds were obtained starting from the key imidazole intermediate, 5‐amino‐1‐phenyl‐methyl‐2‐mercapto‐1H‐imidazole‐4‐carboxylic acid amide 5 , readily derived from the base catalyzed rearrangement of a thiazole, 5‐amino‐2‐phenylmethylaminothiazole‐4‐carboxylic acid amide 4 . Alkylation of the thiol function on 5 with phenylmethyl and allylic chlorides gave compounds 6 and 7 respectively. Cyclization of 6 with a variety of esters afforded 8‐phenylmethylthiohypoxanthines, 8–11 . Similarly, 7 was cyclized to 8‐allylthiohypoxanthines, 20–21 . Compound 5 was also cyclized, but formed 8‐mercaptohypox‐anthines, 22–24 . Alkylation of 8‐mercaptohypoxanthines afforded 8‐alkylthiohypoxanthines, 8, 9,25 and 26 (see Scheme 2). Chlorination of 9–11 afforded 16–18 ; adenine 19 was derived from 16 . Oxidation of hypox‐anthines 8–11 with m‐chloroperbenzoic acid gave the corresponding 8‐phenylmethylsulfonyl derivatives 12 ‐ 15 . These derivatives proved resistant to nucleophilic displacement reactions with primary amines. 相似文献
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Yunus Taskesenligil Ferruh Lafzi Haydar Kilic Nurullah Saracoglu 《Journal of heterocyclic chemistry》2019,56(12):3289-3296
Pd(II)‐catalyzed C‐H arylations of 5‐aminoindole using iodobenzenes as aryl source was studied. Despite pivalamide directing group at 5‐position of the indole, the direct C2‐arylation of the indole observed in high yields and with high regioselectivity. 相似文献
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Mario Tenne Yvonne Unger Thomas Strassner 《Acta Crystallographica. Section C, Structural Chemistry》2012,68(8):m203-m205
The title platinum(II) complex, [Pt(C10H8BrN2)(C5H7O2)], has a bidentate cyclometallated phenylimidazolylidene ligand and an acetylacetonate spectator ligand, which form a distorted square‐planar coordination environment around the PtII centre. In the solid state, the molecules are oriented in a parallel fashion by intermolecular hydrogen bonding and π–π and C—H...π interactions, while close Pt...Pt contacts are not observed. The structure is only the second example for this new class of compounds. 相似文献
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Chandrababu Naidu Kona Yuji Nishii Masahiro Miura 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(29):9961-9965
Indoles and their analogues have been one of the most ubiquitous heterocycles during the past century, and extensive studies have been conducted to establish practical synthetic methods for their derivatives. In particular, selective functionalization of the poorly reactive benzenoid core over the pyrrole ring has been a great challenge. Reported herein is an iridium‐catalyzed direct alkynylation of the indole C4‐ and C7‐positions with the assistance of sulfur directing groups. This transformation shows a wide range of functional‐group tolerance with exceptional site selectivity. The directing group can be either easily removed or transformed after catalysis. The synthetic utility of the alkyne fragment is demonstrated by the derivatization into the core structure of natural indole alkaloids. 相似文献
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The Oshima? Nozaki (Et2AlI) condensation of isolevoglucosenone ( 4 ) with 2,6‐anhydro‐3,4,5,7‐tetra‐O‐benzyl‐D ‐glycero‐D ‐gulo‐heptose ( 5 ) gave an enone 6 that was converted with high stereoselectivity to 3‐C‐[(1R)‐2,6‐anhydro‐D ‐glycero‐D ‐gulo‐heptitol‐1‐C‐yl]‐2,3‐dideoxy‐D ‐arabino‐hexose ( 1 ; 1 : 1 mixture of α‐ and β‐D ‐pyranose), and to 3‐C‐[(1R)‐2,6‐anhydro‐D ‐glycero‐D ‐gulo‐heptitol‐1‐C‐yl]‐2,3‐dideoxy‐D ‐lyxo‐hexose ( 2 ; 2.7 : 1.4 : 1.0 : 1.4 mixture of α‐D ‐furanose, β‐D ‐furanose, α‐D ‐pyranose, and β‐D ‐pyranose). The Oshima? Nozaki (Et2AlI) condensation of levoglucosenone ( 17 ) with aldehyde 5 gave an enone 18 that was converted with high stereoselectivity to 3‐C‐[(1R)‐2,6‐anhydro‐D ‐glycero‐D ‐gulo‐heptitol‐1‐C‐yl]‐3,4‐dideoxy‐α‐D ‐arabino‐hexopyranose ( 3 ; single anomer). 相似文献
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Copper‐Mediated C6‐Selective Dehydrogenative Heteroarylation of 2‐Pyridones with 1,3‐Azoles
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Riko Odani Dr. Koji Hirano Prof. Dr. Tetsuya Satoh Prof. Dr. Masahiro Miura 《Angewandte Chemie (International ed. in English)》2014,53(40):10784-10788
A copper‐mediated C6‐selective dehydrogenative heteroarylation of 2‐pyridones with 1,3‐azoles has been developed. The reaction proceeded smoothly by twofold C? H cleavage even in the absence of noble‐metal catalysts. The observed site selectivity was directed by a pyridyl substituent on the nitrogen atom of the pyridone ring. This directing group was readily removed after the coupling event, thus leading to 2‐pyridone derivatives with a free N? H group. Moreover, in some cases, catalytic turnover of the Cu salt was also possible with the ideal terminal oxidant: molecular oxygen in air. 相似文献
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Pale yellow single crystals of [O=C(NPPh3)C(I)=C(NPPh3)‐C(NPPh3)2]+I‐·1.5 thf ( 1 ·1.5 thf) have been obtained by the reaction of INPPh3 with thallium in thf suspension. They are characterized by IR spectroscopy and by a crystal structure determination. 1 ·1.5 thf crystallizes in the monoclinic space group P21/n, Z = 4, lattice dimensions at ‐83?C: a = 1101.7(1), b = 3449.0(2), c = 2000.4(1) pm, β = 104.88(1)?, R1 = 0.0382. 1 can be understood as a cationic variation of (Z)‐2‐butenale in which all H atoms are substituted by triphenylphosphoraneimine residues and by a iodine atom, respectively. 相似文献
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Jos Prez Luis García Jose Luis Serrano Eduardo Prez Gregorio Snchez Jorge Vives 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(7):m404-m406
The anionic complex in the title compound, (C16H36N)2[Pd2(C12H12O8)2Cl2], lies on a centre of inversion, so that the {Pd2(μ‐Cl)2} core is planar, which is the most frequent conformation found for complexes containing this moiety in the Cambridge Structural Database [October 2001 Release; Allen & Kennard (1993). Chem. Des. Autom. News, 8 , 1, 31–37]. This dinuclear complex has a Pd?Pd distance of 3.5119 (4) Å. The bite angle of the chelating ligand [79.79 (8)°] distorts the square‐planar coordination around the metal atom. 相似文献
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《Angewandte Chemie (International ed. in English)》2017,56(48):15456-15460
A straightforward access to a hitherto unknown C 3‐symmetric tricyclic triol both in racemic and enantiopure forms has been developed. Treatment of 7‐tert ‐butoxynorbornadiene with peroxycarboxylic acids provided mixtures of C 1‐ and C 3‐symmetric 3,5,7‐triacyloxynortricyclenes via transannular π‐cyclization and replacement of the tert ‐butoxy group. By refluxing in formic acid, the C 1‐symmetric esters were converted to the C 3‐symmetric formate. Hydrolysis gave diastereoisomeric triols, which were separated by recrystallization. Enantiomer resolution via diastereoisomeric tri(O ‐methylmandelates) delivered the target triols on a gram scale. The pure enantiomers are useful as core units of dopants for liquid crystals. 相似文献