Palladium acyclic diaminocarbene (ADC) complexes of the type cis-[(R1NH)(R2)methylidene]Pd(OCOCF3)2(CNR1) [R1 = 2,4,6-(CH3)3C6H2: R2 = NC4H8 (1); NC5H10 (2)] have been synthesized and structurally characterized. These 1 and 2 complexes are effective precatalysts for the one-pot tandem Hiyama alkynylation/cyclization reaction producing benzofuran compounds and, quite interestingly, higher yields of ca. 33−52 % were observed for the aryl triethoxysilylalkyne substrates as compared to that of ca. 15−21 % for the aliphatic triethoxysilylalkyne substrates. The 1 and 2 complexes were conveniently prepared by the salt metathesis reaction of the chloro derivatives with AgOCOCF3 in excellent yields (ca. 84−94 %) under ambient conditions.
- acyclic diaminocarbene complexes (ADCs)
- benzofuran derivatives
- hiyama alkynylation/cyclization
- one-pot tandem reactions