ChemInform Abstract: Cross‐Coupling Reactions of Halopurines with Aryl‐ and Alkyltrifluoroborates. The Scope and Limitations in the Synthesis of Modified Purines.

Abstract

Purine derivatives R 0540Cross-Coupling Reactions of Halopurines with Aryl-and Alkyltrifluoroborates. The Scope and Limitations in the Synthesis of Modified Purines. -Optimized reaction conditions are developed for the Pd-catalyzed cross-coupling reaction of halopurines with aryltrifluoroborates. In general, alkyl-substituted (II) show poor reactivity. -(HASNIK, Z.; POHL, R.; HOCEK*, M.; Synthesis

ChemInform Abstract: Potassium Trifluoroborate Salts as Convenient, Stable Reagents for Difficult Alkyl Transfers

“…Another recent publication outlined the cross-coupling of halopurines with potassium methyltrifluoroborate to generate substituted purines, which represent an important class of biologically active compounds [xxxi]. Notably, the use of Pd(OAc) 2 and trisodium triphenylphosphine-3,3′,3″-trisulfonate (TPPTS) under microwave conditions facilitated the cross-coupling of potassium methyltrifluoroborate with 6-chloropurine (Scheme 7).…”

“…Additionally, the use of Pd(OAc) 2 and di(1-adamantyl)- n -butyl-phosphine ( n -BuPAd 2 ) facilitated the cross-coupling of potassium cyclopropyltrifluoroborate and 6-chloropurine to generate the cyclopropyl-substituted product in good yield [31] (Scheme 9). …”

Cross-Coupling Reaction with Lithium Methyltriolborate

“…In addition, cross-coupling of alkylboronic acids is complicated by protodeboronation and, as a result, excess boronic acids are used in the reaction for complete consumption of electrophiles. A recent advance is the use of methylboron reagents, such as MeLi/ B -MeO-9-BBN [ 19 ], 10-methyl-9-oxa-10-borabicyclo[3.3.1]decane [ 20 , 21 ] and MeBF 3 K [ 22 , 23 , 24 , 25 , 26 , 27 ], for methylation of aryl compounds. However, the use of large amounts of a base, especially a strong base, may be a major limitation for these applications [ 28 ].…”