Group IVB organometallic derivatives: Synthesis and 13C NMR spectra of new silyl and stannyl isoxazoles

Improving the Nicotinic Pharmacophore with a Series of (Isoxazole)methylene-1-azacyclic Compounds: Synthesis, Structure−Activity Relationship, and Molecular Modeling

“…To a solution of 3-methyl-5-trimethylsilanylmethylisoxazole 39 (12) (3.38 g, 20.0 mmol) in THF (100 mL) under N2 was added n-butyllithium (2.5 M in hexanes, 8.0 mL, 20 mmol) dropwise at -78 °C. After the mixture was stirred for 60 min at -78 °C, a solution of (R/ S)-1-azabicyclo [2.2.1]heptan-3-one 9 in THF (20 mL) was added dropwise and stirring continued at -78 °C for 60 min, whereupon concentrated HCl (10 mL) was added, and the reaction was allowed to warm to 20 °C.…”

Five‐Membered Heterocycles: 1,2‐Azoles. Part 2. Isoxazoles and Isothiazoles

“…Thus, the 3,5-dimethylisoxazole 252a reacts with BuLi to give specific metallation at C5 methyl group and the subsequent treatment with Me 3 SiCl affords 253a in 70% yield (Scheme 9.100). Regioselective metallation at the same position is observed for trimethylisoxazole 252b [329,330]. 4-Metalloisoxazoles are generally prepared by halogen-metal exchange reactions [330].…”

“…Regioselective metallation at the same position is observed for trimethylisoxazole 252b [329,330]. 4-Metalloisoxazoles are generally prepared by halogen-metal exchange reactions [330]. Direct lithiation of 3-(Boc-amino)isoxazole 254 and 5-(Boc-amino)isoxazole 256 using BuLi or s-BuLi/TMEDA as the lithiating reagents, respectively, has been reported (Scheme 9.101) [331].…”

Alkoxy(alkyl)silylalkyl derivatives of nitrogen-containing heterocycles

“….SiMe n (OMe) 37n , where n = 0 or 1, were synthesised in 65% ± 86% yields by the reaction of S-sodium derivatives of 8-mercaptoquinoline, 2-mercaptobenzooxazole, 2-mercaptobenzothiazole and 2-mercaptobenzoimidazole with trimethoxy-(chloromethyl)and dimethoxymethyl(chloromethyl)silanes (1) in a polar aprotic solvent (DMF, DMSO) for 2 ± 3 h at 80 ± 90 8C. 40 ± 42 SNa N + ClCH2SiMen(OMe)37n The synthesis of trimethylsilylalkyl-substituted pyrrole, 43, 44 piperidine, 45 pyridine, 46 ± 49 2-pyridone, 50 pyrrolidine, 51,52 pyrazole, imidazole, benzoimidazole, 53 quinoline, 54 ± 56 3,4-dimethylisoxazole, 57,58 2-mercaptobenzothiazole, 59,60 benzothiazole, 61 indole, 62 tetrazole, 63 pyrimidine 64 and carbazole 65 makes wide use of C-, N-or S-lithium derivatives of these heterocycles. The latter are obtained by the reaction of the corresponding heterocyclic compounds with RLi (R = Me, Bu n , Bu t , Ph, NPr i…”