| Abstract |
The reaction between the equimolar amounts of cis-[PdCl2(CNR1)(2)] (R-1 = cyclohexyl (Cy) (1), tBu (2)) and the carbohydrazides (RCONHNH2)-C-2 (R-2 = Ph (5), 4-ClC6H4 (6), 3-NO2C6H4 (7), 4-NO2C6H4 (8), 4-CH3C6H4 (9), 3,4-(MeO)(2)C6H3 (10), naphth-1-yl (11), fur-2-yl (12), 4-NO2C6H4CH2 (13), Cy (14), 1-(4-fluorophenyl)-5-oxopyrrolidin-3-yi (15), (pyrrolidin-1-yl)C(0) (16)) proceeds in refluxing CHCl3 for ca. 4 h. A subsequent workup provided the amino-carbene species cis-[PdCl2\C(NHNHC(O)R-2)=N(H)R-1\-(CNR1)] (18-33) in good to excellent (80-95\%) isolated yields. The coupling of equimolar amounts of cis-[PdCl2(CNR1)(2)] (R-1 = Cy (1), tBu (2), 2,6-Me2C6H3 (XYI) (3), 2-Cl-6-MeC6H3 (4)) and PhSO2NHNH2 (17) occurs similarly and affords the aminocarbenes cis-[PdCl2\C(NHNHS(O)(2)Ph)=N(H)R-1\(CNR1)] (34-37; 60-90\%). Complexes 18-37 were characterized by elemental analyses (C, H, N), ESV+-MS, IR, and 1D (H-1, C-13\H-1\) and 2D (H-1,H-1-COSY, H-1,C-13-HMQC, H-1,C-13-HSQC, HMBC) NMR spectroscopy, as well as by X-ray diffraction for three species (34, 37, and 38). The catalytic properties of 18-37 in Suzuki Miyaura cross-coupling in aqueous medium were evaluated, and 18-37 showed remarkable activity (0.001-0.01 mol \% catalyst loading). The scope of the catalytic process covers sterically unhindered and sterically demanding aryl bromides and aryl iodides bearing donor and/or acceptor substituents and activated aryl chlorides. All organohalides reacted with a range of arylboronic acids at 80 degrees C within 2 h (100 degrees C and 3 h for the chlorides), providing target diaryis in yields up to 99\% and with maximum TONs of 9.9 X 10(3) (for aryl iodides), 4.7 X 104 (for aryl bromides), and 9.2 X 10(3) (for aryl chlorides). |
