D. A Evans, N. Finney Hydrazone Transformations-5 Chem 206 Tosylhydrazone-Based Fragment Coupling Stereoselective Construction of trisubstituted olefins AG. Myers, P.J. Kukkola JACS, 1990, 112, 8208. 2)Et3N, TBSOTf I TBS R-U LiN RR CF3CH2OH R /p g O CHo 4) AcOH, F3CCH20 TBS=t-BuMe SH -78→t Ratio Z: E Yield The monoalkyl azene a decomposes via a radical pathway A.G. Myers etal. JACS, A Complex Application: ASmith etal. JACS 1999, 121, 7423 TBS Meo OMet-BuLi(1.8 eq. ether,-78°c OMe as above) 82%,>201c3R H N N TBS Ts R H O R' Li R R' LiN N TBS Ts R R' R R' N NH O CHO O O O O Me Me Me Me R' Li AcOH CF3CH2OH A RO Ph Me Me RO Me N NHSO2AR H Ph Me LI H Et Li H Me Li Me H Me CHO Me H Me H Et Li H Me CHO Me H Me Me Li Me H Bu Bu HO OH HO OH Me Me MeO OMe MeO OMe Me RO Bu Bu Me Me I MeO OMe Bu MeO OMe Me RO N Bu N TBS Ts O O O O O Me Me Me Me N N SO2Ar TBS Me Li Me H RLi Me Me H Me H Et CH3 O O O O O Me Me Me Me H Me Et Me Me H Me H Me Et O O O O O Me Me Me Me H Et Me O O O O O Me Me Me Me N Me Me H N H D. A. Evans, N. Finney Hydrazone Transformations-5 Chem 206 Tosylhydrazone-Based Fragment Coupling TBS = t-BuMe2Si– –78 °C –78 ® rt The monoalkyl azene A decomposes via a radical pathway 95% 16 cases reported: A. G. Myers etal. JACS, 1998, 120, 8891. 50:50 79% <5:95 1) H2NNHTs 2) Et3N, TBSOTf 3) RLi Ratio Z:E 81% Yield Stereoselective Construction of Trisubstituted Olefins (Z) 4) AcOH, F3CCH2OH (as above) 82%, >20:1 90%, ca. 2:1 (as above) (E) Cylindrocyclophane-F t-BuLi (1.8 eq.) ether, -78 °C (73%) A Complex Application: A. Smith etal. JACS 1999, 121, 7423 A. G. Myers, P. J. Kukkola JACS, 1990, 112, 8208