Polymer-Assisted horner–Emmons olefination using PASSflow reactors: pure products without purification
摘要:
A PASSflow protocol for the 1-Horner-Emmons olefination of aldehydes using polymer-bound hydroxide ions in flow-through reactors is presented which allows preparation of alkenes in very high yield with minimal purification. (C) 2002 Elsevier Science Ltd. All rights reserved.
Copper-Catalyzed Asymmetric Conjugate Additions of Bis(pinacolato)diboron and Dimethylzinc to Acyl-<i>N</i>-methylimidazole Michael Acceptors: A Highly Stereoselective Unified Strategy for 1,3,5,...<i>n</i> (OH, Me) Motif Synthesis
作者:Jimmy Lauberteaux、Christophe Crévisy、Olivier Baslé、Renata Marcia de Figueiredo、Marc Mauduit、Jean-Marc Campagne
DOI:10.1021/acs.orglett.9b00479
日期:2019.3.15
(OH, Me) motifs based on consecutive copper-catalyzed asymmetricconjugate borylation (ACB) and methylation (ACA) reactions involving α,β-unsaturated 2-acyl-N-methylimidazoles is described. Good yields and high diastereoselectivities have been obtained in ACA and ACB reactions for both matched and mismatched pairs as illustrated in the synthesis of syn/anti and anti/anti (Me, OTBS, Me) and (OH, OTBS
Synthetic Studies toward the Total Synthesis of Tautomycetin
作者:Danilo Pereira de Sant’Ana、Celso de Oliveira Rezende Júnior、Jean-Marc Campagne、Luiz Carlos Dias、Renata Marcia de Figueiredo
DOI:10.1021/acs.joc.9b01712
日期:2019.10.4
The studies culminating in the synthesis of two large subunits of tautomycetin are described. The first one, fragment C1-C12 that has an anti-1,3-dimethyl system and a terminal diene unit, was accomplished in 10 linear steps in 7.4% overall yield. The second one, fragment C13-C25 which bears the sensitive anhydride framework and the majority of the stereogenic centers, was prepared in 13 linear steps
The compound, (E)-(1R,3R)-5-[(R)-11-hydroxy-7,11-dimethyl-dodec-2-enylidene]-cyclohexane -1,3-diol of the formula I: ##STR1## is useful in the treatment or prevention of hyperproliferative skin diseases, particularly psoriasis, basal cell carcinomas, disorders of keratinization and keratosis; or for reversing the conditions associated with photodamage.
compounds to afford valuable chiral β-amino acid derivatives (up to >99:1 e.r.) using dioxazolones as a robust amino source. A wide range of alkyl-substituted olefins conjugated to esters, amides, thioesters, and ketones were successfully amidated at the β-position with excellent enantioselectivity for the first time. Combined experimental and computational mechanistic studies supported our working hypothesis
Four new compounds, citrusosides A-D (1-4), and 15 known compounds were isolated from the hexanes and CH2Cl2 extracts of the peels of Citrus hystrix fruits. Compound 1 is a 1-O-isopropyl-6-O-beta-D-glucopyranosyl ester of 5 '',9 ''-dimethyl-2 '',8 ''-decadienoic acid. Compounds 2-4 possess a 1-O-isopropyl-beta-D-glucopyranosyl and a dihydroxyprenylfuranocoumarin moiety conjugated to the 3-hydroxy-3-methylglutaric acid as diesters. Several furanocoumarins were evaluated for their cholinesterase inhibitory activity. (R)-(+)-6'-Hydroxy-7'-methoxybergamottin, (R)-(+)-6',7'-dihydroxybergamottin, and (+)-isoimparatorin showed IC50 values of 11.2 +/- 0.1, 15.4 +/- 0.3, and 23 +/- 0.2 mu M. respectively. Bioassay results indicated that the presence of a dioxygenated geranyl chain in the test compounds is crucial for the inhibitory activity.