... Tetrahedron Letters. Volume 30, Issue 6, 1989, Pages 651–654. ... Abstract. The combination of (dba) 3 Pd 2 ·CHCl 3 plus a car☐ylic acid effectively catalyzes cyclization of 1,6-enynes in which asymmetric induction may be achieved by use of enantiomerically pure car☐ylic acids. ...