(3 + 2)-Cycloaddition of Donor–Acceptor Cyclopropanes with Selenocyanate: Synthesis of Dihydroselenophenes and Selenophenes
作者:Anu Jacob、Peter G. Jones、Daniel B. Werz
DOI:10.1021/acs.orglett.0c03329
日期:2020.11.6
We present a Lewis-acid-catalyzed (3 + 2)-cycloaddition of donor–acceptor cyclopropanes and selenocyanate (as its tetramethylammonium salt) for the synthesis of dihydroselenophenes. The transformation proceeded with moderate to excellent yields and showed a high functional group tolerance. Further oxidation using DDQ delivered selenophenes.
Formal Insertion of Thioketenes into Donor–Acceptor Cyclopropanes by Lewis Acid Catalysis
作者:André U. Augustin、Marius Busse、Peter G. Jones、Daniel B. Werz
DOI:10.1021/acs.orglett.7b03961
日期:2018.2.2
Donor–acceptorcyclopropanes were reacted under Lewis acid catalysis with 3-thioxocyclobutanones as surrogates for disubstituted thioketenes. A broad scope of 2-substituted tetrahydrothiophenes with a semicyclic double bond was obtained under mild conditions with high functional group tolerance and in excellent yield. A sequence of a formal [3 + 2]-cycloaddition followed by the subsequent release of
(3+2)-Cycloaddition of Donor–Acceptor Cyclopropanes with Thiocyanate: A Facile and Efficient Synthesis of 2-Amino-4,5-dihydrothiophenes
作者:Daniel B. Werz、Anu Jacob、Philip Barkawitz、Ivan A. Andreev、Nina K. Ratmanova、Igor V. Trushkov
DOI:10.1055/a-1385-2385
日期:2021.6
An easy and efficient route to obtain 2-amino-4,5-dihydrothiophenes is presented. A formal (3+2)-cycloaddition of donor–acceptor cyclopropanes and ammonium thiocyanate catalyzed by Yb(OTf)3 delivers the desired products in good to excellent yields. A broad range of functional groups is tolerated during this process.
Donor–Acceptor Cyclopropanes as 1,2-Dipoles in GaCl<sub>3</sub>-Mediated [4 + 2]-Annulation with Alkenes: Easy Access to the Tetralin Skeleton
作者:Roman A. Novikov、Anna V. Tarasova、Victor A. Korolev、Evgeny V. Shulishov、Vladimir P. Timofeev、Yury V. Tomilov
DOI:10.1021/acs.joc.5b01179
日期:2015.8.21
A new process for (4 + 2)-annulation of donor–acceptorcyclopropanes (DACs) with unsaturated compounds in the presence of anhydrous GaCl3 has been developed. In this process, DACs act as sources of formal1,2- and 1,4-dipoles to give polysubstituted tetralins in high yields and with high regio- and diastereoselectivity. Alkenes with both aryl and alkyl substituents at the double bond undergo this reaction
Stereospecific Formal [3+2] Dipolar Cycloaddition of Cyclopropanes with Nitrosoarenes: An Approach to Isoxazolidines
作者:Shyamal Chakrabarty、Indranil Chatterjee、Birgit Wibbeling、Constantin Gabriel Daniliuc、Armido Studer
DOI:10.1002/anie.201400885
日期:2014.6.2
The MgBr2‐catalyzed formal [3+2] cycloaddition of donor–acceptor activated cyclopropanes with nitrosoarenes offers a novel approach to various structurally diverse isoxazolidines. The reactions, which are experimentally easy to conduct, occur with complete stereospecificity and perfect control of regioselectivity. Product isoxazolidines can be readily transformed into α‐amino lactones by reductive