Reactions of substituted pyridines with electrophilic boranes

The lutidine derivative (2,6-Me-2)(4-Bpin)C5H2N when combined with B(C6F5)(3) yields a frustrated Lewis pair (FLP) which reacts with H-2 to give the salt [(2,6-Me-2)(4-Bpin)C5H2NH][HB(C6F5)(3)] (1). Similarly 2,2 '-(C5H2(4,6-Me-2)N)(2) and (4,4 '-(C5H2(4,6-Me-2)N)(2) were also combined with B(C6F5)(3) and exposed to H-2 to give [(2,2 '-HN(2,6-Me-2)C5H2C5H2(4,6-Me-2)N][HB(C6F5)(3)] (2) and [(4,4 '-HN(2,6-Me-2)C5H2C5H2(2,6-Me-2)N] [HB(C6F5)(3)] (3), respectively. The mono-pyridine-N-oxide 4,4 '-N(2,6-Me-2)C5H2C5H2(2,6-Me-2)NO formed the adduct (4,4 '-N(2,6-Me-2)C5H2C5H2(2,6-Me-2)NO)(B(C6F5)(3)) (4) which reacts further with B(C6F5)(3) and H-2 to give [(4,4 '-HN(2,6-Me-2)C5H2C5H2(2,6-Me-2) NO)B(C6F5)(3)] [HB(C6F5)(3)] (5). In a related sense, 2-amino-6-CF3-C5H3N reacts with B(C6F5)(3) to give (C5H3(6-CF3)NH)(2-NH(B(C6F5)(3))) (6). Similarly, the species, 2-amino-quinoline, 8-amino-quinoline and 2-hydroxy-6-methyl-pyridine were reacted with B(C6F5)(3) to give the products as (C9H6NH)(2-NHB(C6F5)(3)) (7), (C9H6N)(8-NH2B(C6F5)(3)) (8) and (C5H3(6-Me)NH)(2-OB(C6F5)(3)) (9), respectively; while 2-amino-6-picoline, 2-amino-6-CF3-pyridine, 2-amino-quinoline, 8-amino-quinoline and 2-hydroxy-6-methyl-pyridine react with ClB(C6F5)(2) to give the species (C5H3(6-R)NH)(2-NH-(ClB(C6F5)(2))) (R = Me (10), R = CF3 (11)) (C9H6NH)(2-NH(ClB(C6F5)(2))) (12), (C9H6N)(8-NH2ClB(C6F5)(2)) (13) and (C5H3(6-Me)NH)(2-OClB(C6F5)(2)) (14), respectively. In a similar manner, 2-amino-6-picoline and 2-amino-quinoline react with B(C6F5)(2)H to give (C5H3(6-Me)NH)(2-NH(HB(C6F5)(2))) (15) and (C9H6NH)(2-NH(HB(C6F5)(2))) (16). The corresponding reaction of 8-amino-quinoline yields (C9H6N)(8-NHB(C6F5)(2)) (17). In a similar fashion, reaction of 2-amino-6-CF3-pyridine resulted in the formation of (18) formulated as (C5H3(6-CF3)N)-(2-NH(B(C6F5)(2)). Finally, treatment of 15 with iPrMgCl gave (C9H6N)(2-NH(B(C6F5)(2))) (19). Crystallographic studies of 1, 2, 4, 6, 7, 10, 11, 12 and 15 are reported.