The trichlorophenyl-, dichlorodiphenyl-, and chlorotriphenylgermanes undergo Pd-catalyzed cross-couplings with aryl bromides and iodides in the presence of tetrabutylammonium fluoride in toluene with addition of the measured amount of water. One chloride ligand on the Ge center allows efficient activation by fluoride to promote transfer of one, two or three phenyl groups from the organogermanes. The corresponding chlorophenylstannanes were found to be more reactive than chlorophenylsilanes, which in turn were more effective than chlorophenylgermanes. One chloride ligand on Ge or Si center allows efficient activation by fluoride to promote transfer of up to three aryl groups from germane or silicon. However, no haloligand was necessary to be present on Sn center, since tetraphenyltin efficiently transferred up to four phenyl groups during fluoride-promoted couplings with aryl halides. 19F NMR studies suggested formation of the fluorophenylgermanes and the hypervalent germanate species as possible intermediates.

The trichlorophenyl,-dichlorodiphenyl,-and chlorotriphenylgermanes undergo Pd-catalyzed crosscouplings with aryl bromides and iodides in the presence of TBAF in toluene with addition of the measured amount of water. One chloride ligand on the Ge center allows efficient activation by fluoride to promote transfer of one, two or three phenyl groups from the organogermane precursors.The Pd-catalyzed cross-coupling of organogermanes has thus far received much less attention 1 than the couplings involving organostannanes and organosilanes. 2 This is due to the lower reactivity of tetracoordinated organogermanium species, the less developed syntheses of vinyl/aryl germanyl derivatives, and the higher cost of germanium relative to silicon. 3 The carbagermatranes 1, with internal coordination of nitrogen to germanium, were the first examples of reactive tetracoordinated germanes applied to Pd-catalyzed cross-coupling reactions with aryl bromides 4 (Figure 1). The oxagermatranes 2 were found to be more efficient than carbagermatranes and triethoxygermanes. 5,6 Fluoride-promoted couplings with aryltri(2-furyl)germanes 7 and NaOH-activated couplings with arylgermanium trichlorides 8 or their hydrolyzed and stable sesquioxide alternatives 9 were also reported. The bis(2-naphthylmethyl) arylgermanes 3 were developed as photochemically activated arylgermanes for the synthesis of biaryls. 10,11 The vinyl tris(trimethylsilyl)germanes 4 were employed as transmetalation reagents in "ligand-and fluoride-free" coupling reactions with halides under oxidative wnuk@fiu.edu. † On faculty leave from

terparts. -In the presence of Bu4NF and water Ph-GeCl3, Ph2GeCl2, and Ph3Ge-Cl are found to undergo effective cross coupling with aryl bromides and chlorides to afford various biaryls. The reaction with alkenyl halides is also possible but gives low yields. The corresponding silanes are more reactive than the germanes and the stannanes are the most active ones. Even Ph4Sn efficiently reacts with aryl bromides and iodides and it can transfer up to 4 phenyl groups. -(PITTELOUD, J.-P.; ZHANG, Z.-T.; LIANG, Y.; CABRERA, L.; WNUK*, S. F.; J. Org. Chem. 75 (2010) 23, 8199-8212, http://dx.doi.org/10.1021/jo101848f ; Dep. Chem. Biochem., Fla. Int. Univ., Miami, FL 33199, USA; Eng.) -Jannicke 12-080

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