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Journal of the American Chemical Society
trialkyl and triaryl phosphine ligands. For studies on the effect of
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(11) For computational studies on soluble bases in Pdꢀcatalyzed C–
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ows, R. E.; Norrby, P.ꢀO. J. Org. Chem. 2014, 79, 11961ꢀ11969. In
some cases, soluble bases may be employed to enhance reactions that
do not require bases: Bandaru, S. S. M.; Bhilare, S.; Chrysochos, N.;
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tions of soluble superbases, see: Santanilla, A. B.; Regalado, E.
L.;Pereira, T.; Shevlin, M.;Bateman, K.;Campeau, LꢀC.;Schneeweis,
J.; Berritt, S.; Shi, Z.ꢀC.;Nantermet, P.;Liu, Y.;Helmy, R.;Welch, C.
J.; Vachal, P.; Davies, I. W.; Cernak, T.; Dreher, S. D. Science2015,
347, 49ꢀ53.(c) The use of P2ꢀEt, MTBD, and 2ꢀtertꢀButylꢀ1,1,3,3ꢀ
tetramethylguanidine (BTMG)in the Pdꢀcatalyzed coupling of aryl
amines and aryl halides was reported while this manuscript was under
review: Ahneman, D. T.; Estrada, J. E.; Lin, S.; Dreher, S. D.; Doyle,
A. G. Science DOI: 10.1126/science.aar5169.
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(18) In highꢀthroughput reaction screening, this ligand was found
to be suitable for amide couplings facilitated by DBU. See reference
12a.
(19) Milner, P. J.; Maimone, T. J.; Su, M.; Chen, J.; Müller, P.;
Buchwald, S. L. J. Am. Chem. Soc. 2012, 134, 19922ꢀ19934.
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8460.
(21) Kendall, A. J.; Zakharov, L. N.; Tyler, D. R. Inorg. Chem.
2016, 55, 3079ꢀ3090.
(22) Preliminary mechanistic studies have indicated that there is a
positive order in [DBU] for the coupling of pꢀtolyl triflate and propyl
amine. This suggests that the base is involved in the turnoverꢀlimiting
step.
(23) For examples of this effect observed in methylene groups, see:
(a) Cahill, R.; Cookson, R.C.; Crabb, T. A. Tetrahedron,
1969, 19, 4681ꢀ4709. (b) Cahill, R.; Cookson, R. C.; Crabb, T. A.
Tetrahedron1969, 25, 4711ꢀ4735. (c) Fraser, R. R.; Raby, B. F. J. Am.
Chem. Soc. 1972, 94, 3458ꢀ3463.
2
(24) The variation in J values (~1.0 Hz) is in the range of those
2
observed in J coupling constants of 13C–Au–31P complexes bearing
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