6557-83-1Relevant academic research and scientific papers
Asymmetric Cyclization/Nucleophilic Tandem Reaction of o-Alkynylacetophenone with (Diazomethyl)phosphonate for the Synthesis of Functional Isochromenes
Cai, Liu,Chen, Yuan,Cao, Hao,Wei, Qi,Yang, Yi,Ouyang, Qin,Peng, Yungui
, p. 7597 - 7601 (2019/10/02)
An efficient asymmetric reaction between (diazomethyl)phosphonate with o-alkynylacetophenone has been established by employing different stereocontrol strategy. A variety of isochromenes bearing tetrasubstituted stereocenters and (diazomethyl)phosphonate at the 1-position were prepared in yield up to 99% with enantioselectivity up to 94% enantiomeric excess (ee) for the first time. These functional isochromenes could be transformed to important structural motifs in biologically active compounds. Moreover, density functional theory calculations were conducted to gain insight into the process and the stereoselectivity.
A Selective and Functional Group-Tolerant Ruthenium-Catalyzed Olefin Metathesis/Transfer Hydrogenation Tandem Sequence Using Formic Acid as Hydrogen Source
Zieliński, Grzegorz K.,Majtczak, Jaros?awa,Gutowski, Maciej,Grela, Karol
, p. 2542 - 2553 (2018/03/09)
A ruthenium-catalyzed transfer hydrogenation of olefins utilizing formic acid as a hydrogen donor is described. The application of commercially available alkylidene ruthenium complexes opens access to attractive C(sp3)-C(sp3) bond formation in an olefin metathesis/transfer hydrogenation sequence under tandem catalysis conditions. High chemoselectivity of the developed methodology provides a remarkable synthetic tool for the reduction of various functionalized alkenes under mild reaction conditions. The developed methodology is applied for the formal synthesis of the drugs pentoxyverine and bencyclane.
In tandem or alone: A remarkably selective transfer hydrogenation of alkenes catalyzed by ruthenium olefin metathesis catalysts
Zieliski, Grzegorz Krzysztof,Samojlowicz, Cezary,Wdowik, Tomasz,Grela, Karol
, p. 2684 - 2688 (2015/04/14)
A system for transfer hydrogenation of alkenes, composed of a ruthenium metathesis catalyst and HCOOH, is presented. This operationally simple system can be formed directly after a metathesis reaction to effect hydrogenation of the metathesis product in a single-pot. These hydrogenation conditions are applicable to a wide range of alkenes and offer remarkable selectivity. This journal is
Ring-Closure Reactions. 22. Kinetics of Cyclization of Diethyl (ο-Bromoalkyl)malonates in the Range of 4- to 21-Membered Rings. Role of Ring Strain
Casadei, Maria Antonietta,Galli, Carlo,Mandolini, Luigi
, p. 1051 - 1056 (2007/10/02)
The kinetics of closure of 1,1-bis(ethoxycarbonyl)cycloalkanes from the anions derived from diethyl (ο-bromoalkyl)malonates have been investigated in Me2SO at 25 degC.Rate constants and effective molarities (EM) have been obtained for the ring sizes 4-13, 17, and 21.This is the first quantitative study on the kinetics of SN2 closure of all-carbon rings, which includes small, common, medium and large rings.The reactivity data span over nine powers of ten, which is the widest reactivity range recorded so far in a cyclization series.Due to the extremely low EM for the 9-, 10-, and 11-membered rings, a special competition technique was developed for these rings.Comparison of the present results with literaturee data on SN2 ring-closure reactions reveals structure-dependent reactivity patterns showing varying features, which are qualitatively accounted for on the basis of structure effects on transition-state strain energies.A dissection of the EM data for the malonate cyclization into strain and probability factors was attempted.Perhaps the most interesting result is a definite tendency for transition-state strain energies to parallel cycloalkane strain energies for the 7-membered and larger rings but not for the smaller rings.In the latter cases the ring product no longer appears to be a proper model for comprehending the transition state.
