Hydroxylated α,β-Unsaturated Nitriles:  Stereoselective Synthesis

Synthesis of Functionalized Bridged Bicyclic Sulfonamides with a Bridgehead Nitrogen Atom

“…We believe that this is due to fragmentation which accompanied lithiation of 3f (Scheme ). This presumption can be justified by previously reported ring cleavages promoted by lithiation of tetrahydropyrans containing sulfinyl or nitrile groups at the β‐position to O ‐atom.…”

Stereoselective conjugate addition of organolithium reagents to unprotected 4-hydroxy-2-cyclopentenones

“…We then turned our attention to the possibility of exerting a ligand assisted nucleophilic addition 8 by deprotonating the OH group with an organomagnesium reagent prior to reaction with lithium acetylides. 9,10 Thus, treatment of compound 4a with t BuMgCl (1.0 equiv.) followed by reaction with 7a (2.3 equiv.)…”

“…In light of the proposed reaction course, we studied the possibility of reducing the amount of lithium acetylides 7 required for conjugate addition with the aid of a second organolithium reagent ( t BuLi) 9 which was presumed to transfer more slowly than the acetylide moiety (Scheme 7). We observed that treatment of compounds 4 with MeMgBr (1.1 equiv.)…”

Skeletal and Stereochemical Diversification of Tricyclic Frameworks Inspired by Ca2+-ATPase Inhibitors, Artemisinin and Transtaganolide D

“…The resulting residue was diluted with water and extracted with Et 2 O. The combined organic extracts were washed with brine, dried over Na 2 SO 4 and concentrated to afford 4 3 (1.49 g, 12.1 mmol, 98%) as a colorless oil.…”

“…To a solution of (30.0 mg, 0.114 mmol) in toluene (4.56 mL, 0.025 M) was added catalyst 14 (9.68 mg, 0.0114 mmol), and the resulting solution was heated to 80 °C for 1 h. The mixture was then concentrated, leaving a residue which was purified by silica-gel column chromatography to afford 34 (22.9 mg, 0.0977 mmol, 86%) as a brown oil. IR (film) ν 3399, 2924, 1443, 1064 cm -1 ; 1 H-NMR (400 MHz, CDCl 3 ) δ 5.83 (1H, m), 5.64 (1H, m), 3 S43 and S44. The structure of 34 was unambiguously determined by X-ray analysis of crystalline p-bromobenzoate ester 52.…”