ABSTRACT
A system for the directed hydrogenation of nitrogen heterocycles is described in which hydrogen is delivered cis to a hydroxymethyl group by a rhodium catalyst with a simple phosphine ligand. The chemistry is applied to the synthesis of the hygric acid moiety of lincomycin and the pipecolic acid moiety of Argatroban. A series of control experiments indicate that the stereoselectivity is a result of a combination of both coordination and hydrogen bonding.
Subject(s)
Amino Acids/chemistry , Amino Acids/chemical synthesis , Catalysis , Chemistry Techniques, Synthetic , Hydrogen Bonding , Hydrogenation , Ligands , Lincomycin/chemistry , StereoisomerismABSTRACT
Asymmetric arylation of 4-fluoroalkyl-2-quinazolinone derivatives with arylboronic acids proceeded smoothly in the presence of a cationic palladium catalyst (1â mol %) coordinated with a chiral phosphinooxazoline (phox) ligand to create the corresponding fluorine-containing arylated dihydroquinazolinones in high yields and with greater than 99 % ee.
ABSTRACT
The first phosphine catalysed Michael addition of arylcyanoacetates to allenoates has been developed, and the ß-selective products with a quaternary center were obtained in excellent yields. This unusual regioselectivity may open new opportunities to access interesting molecular structures.