共查询到20条相似文献,搜索用时 15 毫秒
1.
Anne-Sophie Castanet Jean-Baptiste Véron Asish De Jacques Mortier 《Tetrahedron》2008,64(15):3331-3336
The new sequential stereoselective synthesis of diversely substituted 9H-fluoren-9-ones by ortho-lithiation/Bu3SnCl quench of unprotected benzoic acids followed by Stille cross-coupling reaction and remote metalation is reported. 相似文献
2.
Toshimasa Katagiri Hayato NakanishiKenichi Ohno Takayuki SeikiAkira Isobe Keisuke KataokaKenji Uneyama 《Tetrahedron》2011,67(17):3041-3045
Preparations and reactions of (E)-1-aryl-3,3,3-trifluoro-1,2-di(trimethylsilyl)-1-propenes are described. (E)-1-Aryl-3,3,3-trifluoro-1,2-di(trimethylsilyl)-1-propene was prepared from aryl trifluoromethyl acetylenes via reductive bissilylation by TMSCl/Mg in good yields. The silyl groups of (E)-3,3,3-trifluoro-1,2-di(trimethylsilyl)-1-phenyl-1-propene were substituted by electrophiles in both a stepwise and stereoselective (and/or stereospecific) manner. This compound could be a building block for preparations of substituted trifluoropropenes. 相似文献
3.
Tapas Paul 《Tetrahedron letters》2008,49(21):3363-3367
Several di- and trisubstituted primary (E)-allylic alcohols have been prepared from the corresponding terminal olefins in a highly stereoselective manner (>20:1 E/Z) by sequencing olefin cross-metathesis (CM) with hydride reduction (DIBAL-H) in good yields utilizing only commercially available reagents in a one-pot fashion. The method is a reliable alternative to the direct CM of terminal olefins with allyl alcohol, which is not always stereoselective but rather highly substrate dependent. 相似文献
4.
A highly stereoselective synthesis of almorexant has been achieved using (R)-tert-butanesulfinamide as a chiral source. The chiral tetrahydroisoquinoline core was constructed through allylation of chiral N-sulfinyl imine followed by ring closure of the secondary amide with a tethered halide. The chiral α-phenyl amide was introduced by means of SN2 substitution of (S)-methyl 2-phenyl-2-(tosyloxy)acetate with chiral tetrahydroisoquinoline. 相似文献
5.
Andrea Buzas Xavier F. Le Goff Fabien Gagosz 《Journal of organometallic chemistry》2009,694(4):515-10978
A study concerning the gold(I)-catalyzed transformation of N-(hex-5-enynyl) tert-butyloxycarbamates is described. The mild conditions employed allow the moderately efficient but stereoselective synthesis of a range of bicyclic carbamates following a formal [4+2] cycloaddition process. 相似文献
6.
Stephen HanessianRoger Machaalani 《Tetrahedron letters》2003,44(45):8321-8323
A five-step practical and stereocontrolled synthesis of α- and β-pseudouridines from d-ribonolactone is described. The key step involves a highly stereoselective reduction of a hemiketal C-nucleoside intermediate in each case. Multi-gram quantities of β-pseudouridine can now be made available. 相似文献
7.
Noriyasu Hada 《Tetrahedron letters》2006,47(37):6647-6650
An α-selective galactosylation was demonstrated under various conditions. Among these α-galactoside approaches, high α-selectivity was achieved by the virtue of 4,6-O-di-tert-butylsilylene (DTBS) group. Yield was further improved by the influence of a 2-O-benzylated donor compared to 2-O-benzoylated donor. This method was then applied to the first highly stereoselective synthesis of a newly found trisaccharide glycosphingolipid in Zygomycetes species. 相似文献
8.
A highly practical and concise stereoselective total synthesis of belactosin C and synthetic variants was achieved using an S-proline catalyzed crossed-aldol reaction as the key step. 相似文献
9.
Kazumi OkuroHoward Alper 《Tetrahedron letters》2012,53(36):4816-4818
Palladium-catalyzed intermolecular cyclocarbonylation of diethyl (2-iodoaryl)malonates with N-tosylimines produces 4-ethoxycarbonyl-3,4-dihydroisoquinolin-1(2H)-ones in moderate to good yields. This reaction is highly stereoselective. This protocol involves Mannich addition, and subsequent cyclocarbonylation. 相似文献
10.
Metal triflate catalyzed 1,2-bromoazidation of alkenes was performed using N-bromosuccinimide (NBS) and trimethylsilyl azide (TMSN3) as the bromine and azide sources, respectively. Among the metal triflates, Zn(OTf)2 was found to be the best catalyst. This catalytic process represents a highly regioselective, stereoselective and high yielding method for the synthesis of anti-1,2-bromoazides from a variety of alkenes including α,β-unsaturated carbonyl compounds. 相似文献
11.
Dibenzo tricyclo[3.3.0.02,6]-1,2,5,6-tetrasubstituted octanes, the ‘twisted’ highly strained valence isomers of substituted dibenzo[a,e]cyclooctatetraenes, were synthesized and their structure characterized by single-crystal X-ray analysis. Their skeletal rearrangement was experimentally observed. 相似文献
12.
Ayumu Niida Yoshikazu Sasaki Hirokazu Tamamura Akira Otaka 《Tetrahedron letters》2005,46(24):4183-4186
Regio- and stereoselective anti-SN2′ alkylation of γ-phosphoryloxy-α,β-unsaturated-δ-lactams with organocopper reagents allowing the preparation of N-alkylated-α,δ-substituted-β,γ-unsaturated-δ-lactams as highly functionalized diketopiperazine mimetics is presented. 相似文献
13.
C-Galactosyl and C-ribosyl β-amino acids were prepared by one-pot InCl3-catalyzed Mannich-type three-component condensation (3CC) by combining the corresponding formyl C-glycoside, p-methoxybenzyl amine, and a ketene silyl acetal. In each case the reaction was highly stereoselective and afforded only one single product in good to excellent yields. 相似文献
14.
R. Sateesh Chandra KumarG. Venkateswar Reddy K. Suresh BabuJ. Madhusudana Rao 《Tetrahedron letters》2011,52(34):4382-4384
A highly stereoselective total synthesis of (+)-(8R,8aR)-perhydro-8-indolizidinol is described. Key steps involved in this synthesis are diastereoselective zinc allylation, azido-olefin cyclization and reductive amination followed by cyclization which effectively constructed the indolizidine ring. This contributes a unique approach to the synthesis of indolizidine alkaloids that offers the advantages of brevity and relatively high overall yields. 相似文献
15.
A highly regio- and stereoselective trans-hydrofluorination of N-sulfonyl ynamides has been realized with AgF as the fluorination reagent, affording (Z)-α-fluoroenamides in good to excellent yields. The reaction proceeds under mild reaction conditions and shows good functional group compatibility. 相似文献
16.
V. Shekhar 《Tetrahedron letters》2010,51(6):946-31
A simple and highly efficient first total synthesis of cytotoxic (+)-crassalactone A starting from (R)-mandelic acid is described. The strategy involves the osmium tetroxide-catalyzed cis-hydroxylation and the stereoselective addition of ethyl lithiopropiolate to a chiral aldehyde intermediate as key steps. 相似文献
17.
Ana L. Cardoso Artur M.S. Silva Teresa M.V.D. Pinho e Melo António M. d'A. Rocha Gonsalves 《Tetrahedron》2006,62(42):9861-9871
The 1,3-dipolar cycloaddition of dimethyl acetylenedicarboxylate with nonstabilized azomethine ylides, generated via the decarboxylative condensation of 1,3-thiazolidine-4-carboxylic acids with aldehydes, afforded 5,7a-dihydro-1H,3H-pyrrolo[1,2-c]thiazole derivatives. 2-Substituted-1,3-thiazolidine-4-carboxylic acids led to the stereoselective formation of 5,7a-dihydro-1H,3H-pyrrolo[1,2-c]thiazoles. Quantum-chemistry calculations were carried out allowing the rationalization of the observed stereoselective formation of the anti-dipole. 相似文献
18.
We report a highly efficient method for the synthesis of (Z)-3-ylidenephthalides via intramolecular cyclization of readily available 2-acyl-benzoic acids mediated by TSTU at room temperature. Using this method, diversely substituted (Z)-3-ylidenephthalides have been generated in good to excellent yields. The application of the method is highlighted by gram-scale preparation of the antiplatelet drug n-butylphthalide. 相似文献
19.
The first report on the use of N-sulfinyl benzylcarbamate for the preparation of N-Cbz sulfilimine from the corresponding sulfoxide is reported. The sulfilimine moiety is utilized as an intramolecular nucleophile for the regio- and stereoselective heterofunctionalization of an alkene to furnish a bromo carbamate which is used as a key advanced intermediate in the synthesis of representative α-hydroxy-β-amino acid derivatives. 相似文献
20.
A highly stereoselective method for the synthesis of (E)- and (Z)-α-substituted cinnamates in good yield has been achieved by dehydration reaction of anti- and syn-α-substituted-β-hydroxyphenylpropiolate using EDC. This facile method has been used to synthesize various (E)- and (Z)-α-substituted cinnamates and (E)- and (Z)-α-alkylidene-γ-butyrolactones. The reaction mechanism of this highly stereospecific dehydration using EDC can be elucidated by the ω-dimethylamino group of EDC, which is believed to facilitate the deprotonation step. 相似文献