Biarylphosphanliganden in der palladiumkatalysierten Aminierung

Abstract

In den vergangenen 12 Jahren erfuhr die palladiumkatalysierte Aminierung von Arylhalogeniden eine rasche Entwicklung, die durch die Einführung neuer Ligandenklassen vorangetrieben wurde. Biarylphosphane liefern in diesem Zusammenhang besonders reaktive Katalysatoren. Dieser Aufsatz behandelt Anwendungen solcher Katalysatoren zur C‐N‐Kreuzkupplung in der Synthese von Heterocyclen und Pharmazeutika, in den Materialwissenschaften und in der Naturstoffsynthese.

Utilizing Mor‐DalPhos/Palladium‐Catalyzed Monoarylation in the Multicomponent One‐Pot Synthesis of Indoles

“…[13][14][15][16][17][18][19][20][21] Encouraged by these observations, we envisioned that these two classes of transformations (Buchwald-Hartwig amination [22][23][24][25][26] and ketone monoa-arylation [27][28][29][30] ) could be combined in the development of a new and synthetically useful one-pot, multicomponent indole synthesis starting from commercially available ortho-dihaloarenes, alkyl ketones, and primary amines; one possible reaction sequence of this type is outlined in Scheme 1. Scheme 1.…”

Suzuki–Miyaura Cross‐Coupling under Solvent‐Free Conditions

“…[11] Aryl chlorides that do not contain non-tolerant functional groups can be coupled using PdA C H T U N G T R E N N U N G (OAc) 2 /SPhos giving > 90% yields under solvent-free conditions. Softer bases (K 2 CO 3 or K 3 PO 4 ) were used in the coupling of chlorides bearing sensitive functional groups (entries [4][5][6][8][9][10]. In the latter cases the yields of coupling products varied from good to excellent.…”

“…Various palladium catalysts were tested: well-defined NHC complexes 1-5; [7] expanded ring NHC complexes recently developed in our group 6 and 7; [8] the well-defined catalytic system PdA C H T U N G T R E N N U N G (OAc) 2 /SPhos; [9] as well as the conventional commercially available palladium sources PdCl 2 , Pd 2 A C H T U N G T R E N N U N G (dba) 3 , PdA C H T U N G T R E N N U N G (OAc) 2 , and (Ph 3 P) 2 PdCl 2 .…”

Commentary on “A New, Efficient and Recyclable Lanthanum(III) Oxide‐Catalyzed CN Cross‐Coupling” by S. Narayana Murthy, B. Madhav, V. Prakash Reddy, and Y. V. D. Nageswar, Adv. Synth. Catal. 2010, 352, 3241–3245

“…[1,2] One of the most effective approaches to these compounds has been the use of metal catalysts for the cross-coupling of amines with aryl halides/pseudohalides. Although the utilization of Pd- [2,3] and Cubased [4,5] systems has been the most efficient for these C À N bond-forming processes, a great deal of research has gone into developing catalysts based on other metals. More specifically, Bolm reported several ironbased catalysts for carbon-heteroatom cross-coupling reactions.…”

“…[10] The third possible pathway, which is the most likely, is a traditional metal-catalyzed cross-coupling mechanism. [2,5] Based on the fact that LaA C H T U N G T R E N N U N G (III) has no d electrons we can propose that the employed La 2 O 3 salt is not the active catalyst. Further, due to lanthanums reduction potential we find it unlikely that the DMEDA is a strong enough reducing agent to produce either a La(I) or La(II) species, which could potentially make up the active catalyst.…”