“Endo” and “Exo” Bicyclo[4.2.0]-octadiene Isomers from the Electrocyclization of Fully Substituted Tetraene Models for SNF 4435C and D. Control of Stereochemistry by Choice of a Functionalized Substituent
摘要:
[GRAPHICS]A tandem electrocyclic closure, perceived as the key step in a biomimetic approach to SNF 4435C and D, was tested with 1,1,8-trisubstituted tetraene substrates. The ratio of endo:exo products could be controlled by the choice of the R-z substituent at C-1. On the basis of these results, a short stereoselective route to an advanced SNF 4435 intermediate was devised.
A Convenient Method for the Synthesis of bis-Trifluoroethyl Phosphonoacetates
摘要:
bis-Trifluoroethyl phosphonoacetates were easily obtained by condensation of bis-trifluoroethyl alkylphosphonates with alkyl chloroformates in the presence of 2 equivalents of lithium hexamethyldisilazane (LiHMDS).
described, starting from optically pure (S)-malic acid and methyl (R)-3-hydroxy-2-methylpropionate. The synthesis is highly convergent by coupling the three fragments C1-C6 (fragment D), C7-C10 (fragment C), and C11-C21 (fragment B). Key steps are two stereoselectiveWittig type olefinations to generate the 12,13- and 16,17-double bonds, an enantioselective Mukaiyama aldol addition to synthesize fragment
Stereocontrolled construction of 1,7-dimethyl A.B.C.[6.6.6] tricycles. Part I. Transannular Diels–Alder reactions of 14-membered macrocycles containing <i>trans</i>-dienophiles
作者:Yao-Chang Xu、Andrew L. Roughton、Raymond Plante、Solo Goldstein、Pierre Deslongchamps
DOI:10.1139/v93-152
日期:1993.8.1
5 and dienophile 4 following an intramolecular displacement of an allylic halide by the anion of an appropriately located dimethyl malonate unit. The transannular Diels–Alder reaction performed on 1a led to a mixture of four major tricyclic products, including 34 possessing the unexpected trans-anti-cis (TAC) stereochemistry. When heated at 300 °C, macrocycle 1b underwent an unique conversion via an
Stereoselective Synthesis of Fused Vinylcyclopropanes by Intramolecular Tsuji–Trost Cascade Cyclization
作者:John Braun、Maxim I. Ariëns、Bianca T. Matsuo、Steven de Vries、Ellen D. H. van Wordragen、Brecht D. Ellenbroek、Christophe M. L. Vande Velde、Romano V. A. Orru、Eelco Ruijter
DOI:10.1021/acs.orglett.8b02232
日期:2018.11.2
pendant β-ketoamide or related carbon nucleophile to give γ-lactam-fused vinylcyclopropanes is reported. In addition to two new rings, the products contain three new C-C stereocenters (two of which are quaternary) with a 9:1 dr. Moreover, the reaction proceeds in >94% enantiospecificity with optically enriched starting materials, using an inexpensive carbohydrate as the source of chirality.
Novel compounds, their salts and compositions related thereto having activity against mammalian factor Xa are disclosed. The compounds are useful in vitro or in vivo for preventing or treating coagulation disorders.
Biomimetic Synthesis of Antimalarial Naphthoquinones
作者:Jeremiah P. Malerich、Thomas J. Maimone、Gregory I. Elliott、Dirk Trauner
DOI:10.1021/ja050092y
日期:2005.5.1
The total synthesis of naphthoquinone natural products isolated from the Bignoniaceae plant family is described. Pinnatal, isopinnatal, sterekunthals A and B, pyranokunthones A and B, and anthrakunthone have been prepared along the lines of a biosynthetic proposal involving pericyclic reactions as key steps. The first case of catalysis in oxa 6pi electrocyclizations is reported.
描述了从紫杉科植物家族中分离出的萘醌天然产物的全合成。Pinnatal、isopinnatal、sterekunthals A 和 B、pyranokunthone A 和 B 以及蒽醌已按照涉及周环反应作为关键步骤的生物合成方案制备。报道了 oxa 6pi 电环化催化的第一个案例。