D. A. Evans [2,31-Sigmatropic Rearrangements: Chirality Transfer Chem 206 [2, 3] Sulfur Ylide Rearrangement Using a Chiral Auxiliary Chiral Auxiliaries can also be used in the wittig Rearrangement Kurth Jo1990,55,2286andL1991,32,335 96%de(61%) co2H steps CO2H AMation CH2OR Xc ROCH2 CH2OR P2 97%syn96%de(43%) DBU,·78℃CMe s人 Katsuki. Tet Lett 1986. 27. 4577 Internal Relay of Stereochemistry in C-C Constructions Bu3Sn MeMe Me c3 H7 n-BuL, THF.,8℃ Me OBOM 66%,94:4 diastereoselection> 100: 1 (57% Me C3H,n-BuLi, THi OBOM OBOM Kallmerten TL 1988. 29. 6901 diastereoselection> 100: 1(64% e 64%,493 Kallmerten TL 1993. 34 ee these papers for other applications i Kallmerten TL 1993, 34, 749 Kallmerten SynLet 1992, 845CO2H NH2 Me Me S + O – O Me Me Me S + Me Me Me O O CO2H SH Me Me S O O Me Me Me HBF4 CH2Cl2 N2 S Me Me Me O O CO2H S Me Me Me S O O Me Me Me C3H7 Bu3Sn O Me Me OBOM Me ROCH2 CH2OR O N O Me O O N CH2OR ROCH2 BuLi BuLi OBOM Me Bu3Sn O Me C3H7 S Me + Me Me O O – Me Me Me Me O O S Me Me Me O O S Me HO O XC XC O HO OH OBOM Me Me Me C3H7 C3H7 Me Me Me OH OBOM See these papers for other applications Kallmerten SynLet 1992, 845. Kallmerten TL 1993, 34, 749. Kallmerten TL 1993, 34, 753. n-BuLi, THF, -78 °C Kallmerten TL 1988, 29, 6901. diastereoselection > 100:1 (64%) diastereoselection > 100:1 (57%) n-BuLi, THF, -78 °C Internal Relay of Stereochemistry in C–C Constructions Cp2ZrCl2 97% syn; 96% de (43%) 96% de (61%) Katsuki, Tet Lett 1986, 27, 4577 Chiral Auxiliaries can also be used in the Wittig Rearrangement 64%, 4:93 steps steps DBU, -78 °C Allylation [2,3] Sulfur Ylide Rearrangement Using a Chiral Auxiliary Kurth JOC 1990, 55, 2286 and TL 1991, 32, 335 66%, 94:4 BF4 - D. A. Evans [2,3]-Sigmatropic Rearrangements: Chirality Transfer Chem 206