Palladium-Catalyzed Divergent Reactions of 1,6-Enyne Carbonates: Synthesis of Vinylidenepyridines and Vinylidenepyrrolidines
摘要:
A method for preparing five- or six-membered heterocyclic compounds from enyne carbonates via palladium catalysis was developed. Enyne carbonates were transformed into 3-vinylidene-1-tosylpyridines 2 in the presence of PdI2 as the catalyst. Using Pd(dba)(2) as the catalyst, 3-vinylidene-1-tosylpyrrolidines 3 were obtained. Further functionalizations of compounds 3 were carried out in a one-pot manner.
Styryl ketones of the formula ##STR1## wherein R.sup.8 and R.sup.9 are independently hydrogen or lower alkyl or together represent an additional carbon-carbon bond and R.sup.10 is a group of the formula ##STR2## as well as corresponding compounds of the formula ##STR3## wherein R.sup.10' is a group of formula (a), (b), (d) or (e) or a group of the formula --C(R.sup.18)(R.sup.19)OR.sup.20' ; (f') have mucosa-protective and/or gastric acid secretion-inhibiting properties, such that they can be used for the control or prevention of illnesses of the gastrointestinal tract, especially against gastric ulcers or duodenal ulcers.
Sulfonylative and Azidosulfonylative Cyclizations by Visible-Light-Photosensitization of Sulfonyl Azides in THF
作者:Shaoqun Zhu、Atchutarao Pathigoolla、Grace Lowe、Darren A. Walsh、Mick Cooper、William Lewis、Hon Wai Lam
DOI:10.1002/chem.201704380
日期:2017.12.11
generation of sulfonyl radicals from sulfonyl azides using visible light and a photoactive iridium complex in THF is described. This process was used to promote sulfonylative and azidosulfonylative cyclizations of enynes to give several classes of highly functionalized heterocycles. The use of THF as the solvent is critical for successful reactions. The proposed mechanism of radical initiation involves
Intramolecular Chirality Transfer [2 + 2] Cycloadditions of Allenoates and Alkenes
作者:Yao Xu、Young J. Hong、Dean J. Tantillo、M. Kevin Brown
DOI:10.1021/acs.orglett.7b01420
日期:2017.7.21
Intramolecular chirality transfer [2 + 2] cycloaddition of enantiomerically enriched allenoates and alkenes is presented. The use of a chiral catalyst was found to be critical to achieve high levels of diastereoselectivity compared to use of an achiral catalyst. The method developed leads to highly substituted cyclobutanes that would be difficult to prepare by alternative methods.
Described herein is a visible‐light‐mediated atom‐transfer radical cyclization (ATRC) using 1,6‐enynes as substrates. The sulfonyl chlorides not only served as sulfonyl radical sources but also provided a chlorine atom to enable the formation of highly functionalized cyclic products. This visible‐light‐mediated photocatalytic method is a mild and practical strategy for synthesizing chloroalkyl‐substituted
Functional Metathesis Catalyst Through Ring Closing Enyne Metathesis: One Pot Protocol for Living Heterotelechelic Polymers
作者:Subhajit Pal、Fiorella Lucarini、Albert Ruggi、Andreas F. M. Kilbinger
DOI:10.1021/jacs.7b12805
日期:2018.3.7
Enyne ring closing metathesis has been used to synthesize functional group carrying metathesiscatalysts from a commercial (Ru-benzylidene) Grubbs' catalysts. The new Grubbs-type ruthenium carbene was used to synthesize living heterotelechelic ROMP polymers without any intermediate purification. Olefinmetathesis with a mono substituted alkyne followed by ring closing metathesis with an allylic ether