D. A. Evans Carbonyl[1, 2]&[1, 3] Sigmatropic Rearrangements Chem 206 [1, 3-Sigmatropic Rearrangements The Brook Rearrangement(s) Rsi Rsi A G. Brook Accts. Chem. Research 1974.. 77-84 R Y=C; X=O Ea=8-11 kcal/mol Complete retention of Si OSiR3 Ea= 28 kcal/mol Ph A G. Brook Accts. Chem. Research 1974. 7.77-84 OEt Brook speculates that a hypervalent Si intermediate. Brook has documented that retention at Silicon inversion at Carbon occur might be involved in the rearrangemer Transformations Involving the Brook Rearrangement Y=C: X= C Moser, W.H. The Brook Rearrangement in Tandem Bond Formation Strategies, Tetrahedron 2001, 57, 2065-2084 CH Inversion of si Acylsilanes stereochemistry was noted O R2BH HC H Ea 48 kcal/mol H.Kwartetal,JACS1973.95,8678 Theoretical calculations lead to the conclusion that the concerted [1, 3] E+) sigmatropic rearrangement with retention of Si-configuration should represent the lower energy pathway Yamabe, JACS 1997. 119. 808 12SR3s、 At the present time these rearrangements are not well studiedD. A. Evans Carbonyl [1,2] & [1,3] Sigmatropic Rearrangements Chem 206 "The Brook Rearrangement(s)" [1,3]-Sigmatropic Rearrangements Y C X R3Si R Y C X R R3Si Np Si Ph Me O Ph Y = C; X = O 110 °C Ph O Np Si Me Ph Np Si Ph O Me Ph Complete retention of Si stereochemistry was noted. Ea = 28 kcal/mol A. G. Brook Accts. Chem. Research 1974, 7, 77-84 Brook speculates that a hypervalent Si intermediate might be involved in the rearrangement. Y = C; X = C Np Si CH2 Me Ph H 500 °C H2C H Ph Si Me Np Inversion of Si stereochemistry was noted. Ea = 48 kcal/mol H. Kwart et al., JACS 1973. 95, 8678 Theoretical calculations lead to the conclusion that the concerted [1,3] sigmatropic rearrangement with retention of Si-configuration should represent the lower energy pathway. Yamabe, JACS 1997, 119, 808 At the present time these rearrangements are not well studied, A. G. Brook Accts. Chem. Research 1974, 7, 77-84 C OH R3Si Ph Ph C O H Ph Ph SiR3 Et2NH DMSO Et2NH C O R3Si Ph Ph C O SiR3 Ph Ph Ea ~ 8-11 kcal/mol H N H Et Et H N H Et Et Brook has documented that retention at Silicon & inversion at Carbon occur. Transformations Involving the Brook Rearrangement Moser, W. H. "The Brook Rearrangement in Tandem Bond Formation Strategies," Tetrahedron 2001, 57, 2065-2084 R SiR3 O Acylsilanes Li R El(+) R R3Si O R R O R Li R3Si Li El(+) R O R R3Si El [1,2] Si SiR3 O Cl O Li SiR3 Cu(I) R R R2BH [Ox] R SiR3