Copper-Catalyzed Propargylic Substitution of Dichloro Substrates: Enantioselective Synthesis of Trisubstituted Allenes and Formation of Propargylic Quaternary Stereogenic Centers

Autor:	Laure Guénée, David Grassi, Hailing Li, Thomas Bürgi, Alexandre Alexakis
Rok vydání:	2014
Předmět:	Grignard reagents Chemistry Organic Chemistry Chiral ligand Enantioselective synthesis chemistry.chemical_element General Chemistry Copper Catalysis P ligands Stereocenter Nucleophile Reagent ddc:540 Asymmetric catalysis Organic chemistry Allenes Enantiomer
Zdroj:	Chemistry-A European Journal, Vol. 20, No 50 (2014) pp. 16694-16706
ISSN:	0947-6539
DOI:	10.1002/chem.201404668
Popis:	An easy and versatile Cu-catalyzed propargylic substitution process is presented. Using easily prepared prochiral dichloro substrates, readily available Grignard reagents together with catalytic amount of copper salt and chiral ligand, we accessed a range of synthetically interesting trisubstituted chloroallenes. Substrate scope and nucleophile scope are broad, providing generally high enantioselectivity for the desired 1,3-substitution products. The enantioenriched chloroallenes could be further transformed into the corresponding trisubstituted allenes or terminal alkynes bearing all-carbon quaternary stereogenic centers, through the copper-catalyzed enantiospecific 1,1/1,3-substitutions. The two successive copper-catalyzed reactions could be eventually combined into a one-pot procedure and different desired allenes or alkynes were obtained respectively with high enantiomeric excesses.
Databáze:	OpenAIRE
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