An Easy-To-Use, Regioselective, and Robust Bis(amidate) Titanium Hydroamination Precatalyst: Mechanistic and Synthetic Investigations toward the Preparation of Tetrahydroisoquinolines and Benzoquinolizine Alkaloids
作者:Zhe Zhang、David C. Leitch、Man Lu、Brian O. Patrick、Laurel L. Schafer
DOI:10.1002/chem.200600735
日期:2007.2.23
Amidate-supported titanium amido complexes are efficient and regioselective precatalysts for intermolecular hydroamination of terminal alkynes with primary amines. The synthesis and characterization of the first bis(amidate)-supported titanium-imido complex is reported. Its role as the active catalytic species is suggested in the course of product distribution studies using deuterated substrates. The bis(amidate)-supported
Anti-Markovnikov Intermolecular Hydroamination: A Bis(amidate) Titanium Precatalyst for the Preparation of Reactive Aldimines
作者:Zhe Zhang、Laurel L. Schafer
DOI:10.1021/ol0359214
日期:2003.11.1
[reaction: see text] A bulky bis(N-2',6'-diisopropylphenyl(phenyl)-amidate)titanium-bis(diethylamido) complex was identified as a highly active and regioselective precatalyst for the anti-Markovnikovhydroamination of a wide range of terminal alkyl alkynes with alkylamines. This titanium complex was fully characterized, including its X-ray crystal structure. The reactive aldimine products generated
o-Benzenedisulfonimide as a reusable acid catalyst for an easy, efficient, and green synthesis of tetrahydroisoquinolines and tetrahydro-β-carbolines through Pictet–Spengler reaction
tetrahydro-β-carbolines, using the Pictet–Spengler reaction, was carried out in the presence of a catalytic amount of o-benzenedisulfonimide, which worked as a Brønstedacid organocatalyst. The reaction conditions were mild and green and good target product yields were achieved. The catalyst was easily recovered and purified, ready to be used in further reactions with economic and ecological advantages.