Regioselective Synthesis of New 2,4-(Het)aryl-3H-pyrido[1′,2′:1,5]pyrazolo[4,3-d]pyrimidines Involving Palladium-Catalyzed Cross-Coupling Reactions

Abstract

The design of some novel di-(het)arylated-3H-pyrido[1′,2′:1,5]pyrazolo[4,3-d]pyrimidine derivatives is reported. The series was developed from 1-aminopyridinium iodide, which afforded the key intermediate bearing two thiomethyl and amide functions, each of them useful for palladium catalyzed cross coupling reactions by alkyl sulfur release and C-O activation, respectively. The two regioselective and successive cross-coupling reactions were first carried out in C-4 by in situ C-O activation and next in C-2 by a methylsulfur release. Process optimization furnished conditions leading to products in high yields. The scope and limitations of the methodologies were evaluated and the final compounds characterized.

Effect of Steric Hindrance of Butylammonium Iodide as Interface Modification Materials on the Performance of Perovskite Solar Cells

“…such as 1-aminopyridinium iodide, [36] benzylammonium iodide, and [37] phenylethylammonium iodide. [38] How to select the most suitable ammonium salt to prepare an efficient and stable device has not been solved.…”

“…[ 25,26 ] Many studies reveal that spin coating large‐sized ammonium salt on the 3D perovskite surface can effectively prepare 3D/2D perovskite and passivate 3D perovskite defects, so as to increase the open‐circuit voltage ( V oc ) and stability of the device. [ 27 ] However, there are a large number of different kinds of ammonium salts, for example, short‐chain alkylammonium salts, such as ethylenediammonium diiodide, [ 28 ] propylammonium iodide, [ 29 ] and propane‐1,3‐diammonium iodide, [ 30 ] and long‐chain alkylammonium salts, such as butylammonium iodide, [ 31 ] hexylammonium iodide, [ 32 ] octylammonium iodide, [ 33 ] 1,8‐octanediammonium iodide, [ 34 ] dodecylammonium iodide, [ 35 ] as well as arylammonium salts such as 1‐aminopyridinium iodide, [ 36 ] benzylammonium iodide, and [ 37 ] phenylethylammonium iodide. [ 38 ] How to select the most suitable ammonium salt to prepare an efficient and stable device has not been solved.…”

Access to Mono‐, Di‐ and Tri‐(Het)Arylated Pyrazolo[5,1‐b]oxazoles Using Cyclization, C−H Activation and Suzuki–Miyaura Palladium‐Catalyzed Reactions

“…First, experimental conditions were developed with compound 19, 4-bromoanisole as partner, Pd(OAc) 2 and Xantphos as catalytic system, K 2 CO 3 as base and dioxane as solvent. [31][32][33] In these conditions, the C-3 arylated product 29 was isolated in low yield (22 %, Table 4), with very high selectivity as no trace of other regioisomers was detected. When the ligand was replaced by alkylphosphine PCy 3 , the yield in 29 improved slightly to 30 %.…”

Aminations and arylations by direct C–O activation for the design of 7,8-dihydro-6H-5,8-ethanopyrido[3,2-d]pyrimidines

“…We next focused our attention on using this C-O activation strategy to create a C-C bond instead of a C-N bond under palladium catalysis. 28,40,41 In this tandem procedure, the PyBrop activation was achieved as previously described during 3 h and the reagents necessary to perform the cross coupling reaction were then added. Each parameter of the Suzuki-Miyaura reaction was modulated and the results are summarized in Table 5.…”

“…27 For our own part, our group has developed efficient methodologies to functionalize and obtain biologically active molecules in the pyrimidine series such as pyrido [3-2,d]pyrimidines, pyrido[1 0 ,2 0 :1,5]pyrazolo [3,4-d]pyrimidines or pyrido [1 0 ,2 0 :1,5]pyrazolo [4,3-d]pyrimidine. [28][29][30][31] To escape from atland and evaluate the replicability of our know-how in this poorly explored area, we propose in this paper the access to a 4-aryl-7,8dihydro-1H-5,8-ethanopyrido [3,2-d]pyrimidin-2(6H)-one platform and its further substitution at the C-2 position. 32 This fused arylated skeleton A resulting from the fusion of a quinuclidine and a pyrimidine (quinuclidino-pyrimidinone) was functionalized by aminations or the Suzuki-Miyaura crosscoupling reaction using in situ C-O activation, an innovative and direct method that is particularly powerful to modulate heteroaromatic structures (Fig.…”