681437-21-8Relevant articles and documents
Intermolecular cyclotrimerization of haloketoalkynes and internal alkynes: Facile access to arenes and phthalides
Silvestri,Oakdale
supporting information, p. 13417 - 13420 (2020/11/10)
A highly chemo-and regioselective cyclo(co)trimerization between 3-halopropiolamides and symmetrical internal alkynes is reported. The reaction is catalyzed by CpRuCl(COD) and proceeds under air at ambient temperature in ethanol with no additional precautions. Iodo-, bromo-, and chloropropiolamides, esters, and ketones are viable coupling partners and, in a 2?:?1 stoichiometry relative to internal alkyne, yield fully-substituted arenes in a single step. The highest regioselectivities (96% single isomer) were observed when employing 2° and 3°-halopropiolamides. A mechanistic hypothesis accounting for this selectivity is proposed. Notably, by using 1,4-butynediol as the internal alkyne, in situ lactonization following [2+2+2]-cycloaddition generates therapeutically-relevant phthalide pharmacophores directly. This journal is
Copper-catalyzed highly regio- and stereoselective directed hydroboration of unsymmetrical internal alkynes: Controlling regioselectivity by choice of catalytic species
Semba, Kazuhiko,Fujihara, Tetsuaki,Terao, Jun,Tsuji, Yasushi
experimental part, p. 4179 - 4184 (2012/05/31)
A highly selective synthesis of the αand β products by copper-catalyzed hydroboration utilizing two different catalytic copper species generated from pinacolborane (HBpin) and B2pin2 is reported. Regioselectivity in the crude reaction mixtures is found to be high, and the corresponding a products were isolated in good yields. In the case of an alkyne containing an alkenyl moiety, the regioselectivity decreased to 72:28. In hydroboration reactions catalyzed by other transition metals, selecting between hydrometalation and boryl metalation is difficult because the oxidative addition of HB to a metal center provides an H-M-B species, containing both H-M and B-M bonds. The α and β products are valuable intermediates used in the Suzuki-Miyaura cross-coupling reaction to regioselectively prepare various trisubstituted alkenes of types 5α and 5β.
