TY - DATA T1 - PtCl2-Catalyzed Rearrangement of Methylenecyclopropanes PY - 2006/05/17 AU - Alois Fürstner AU - Christophe Aïssa UR - https://acs.figshare.com/articles/journal_contribution/PtCl_sub_2_sub_Catalyzed_Rearrangement_of_Methylenecyclopropanes/3222010 DO - 10.1021/ja061392y.s001 L4 - https://ndownloader.figshare.com/files/5055937 KW - PtCl 2 KW - CO KW - substituent KW - substrate KW - ROM KW - cyclobutene N2 - Alkylidenecyclopropanes readily convert into cyclobutene derivatives on treatment with catalytic amounts of PtCl2. The reaction is strongly accelerated when performed under an atmosphere of CO (1 atm). The resulting cyclobutenes are isolated in good to excellent yields for substrates bearing aliphatic as well as aromatic substituents R on their olefinic site. If the substituent R, however, is a very electron-rich arene, the cyclobutenes initially formed react further to give dimeric products with a previously unknown 1,2,2a,7a-tetrahydrospiro[cyclobuta[a]indene-7,1‘-cyclobutane skeleton. A mechanism accounting for these experimental observations as well as for a deuterium-labeling experiment is proposed which implies reactive intermediates at the nonclassical cation/carbene interface. Furthermore it is shown that the PtCl2-catalyzed cyclobutene formation can be geared with subsequent ring-opening/ring-closing metathesis (ROM/RCM) events. Finally, a convenient “one pot” method for the preparation of the alkylidenecyclopropane substrates used in this study is presented, which is based on a modified Julia−Kocienski olefination of aldehydes with readily available 1-tert-butyl-1H-tetrazol-5-yl-cyclopropyl sulfone under Barbier conditions. ER -