D. A. Evans Introduction to Organosilicon Chemistry Chem 206 http://www.courses.fasharvardedu/-chem206/ Problems to Contemplate Chemistry 206 Advanced Organic Chemistry Lecture number 33 TBSO OH OTBS KHMDS THF,-78℃c Introduction to Organosilicon Chemistry icon Bonding Considerations Calter, M. A Ph. D Thesis, Harvard University, 1993 Silicon-Proton Analogy C=0 Addition of organosilanes Sigmatropic Rearrangements of Organosilanes The C=o addition illustrated in eq 1 proceeds while the carbon analogue (eq 2) does not. Explain I Anionic(Brook) Rearrangement I Peterson olefination reaction OTMS I Survey of Silicon(and related) Protecting Groups RO-P Reading Assignment for this Lecture RO OR Carey& Sundberg, Advanced Organic Chemistry, 4th Ed. Part B Chapter 9, " C-C Bond Forming Rxns of Boron, Silicon& Tin", 595 OMe Fleming, I; Barbero, A Walter, D "Stereochemical control in using silicon-containing compounds. "Chem. Rev. 1997, 97, 20 Moser, W.H. The brook Rearrangement in Tandem Bond Formation e, C. E: Panek, J.S. selective reactions of chiral allyl- and bonds"chem.Rev.195,95,1293-1316 Provide a mechanism for the indicated transformation Ager, D J. "The Peterson olefination reaction "Org. Reactions 1990, 38, 1-224 Colvin, E. "Silicon in Organic Synthesis " Butterworths, 1981 人 Bois, et al. "Silicon Tethered reactions"Chem. Rev 1995 95. 1253-1277. Matthew d shair Wednesda December 11. 2002 Takeda, Org. Let, 2000, 2, 903-1905D. A. Evans Chem 206 Matthew D. Shair Wednesday, December 11, 2002 http://www.courses.fas.harvard.edu/~chem206/ Reading Assignment for this Lecture: Introduction to Organosilicon Chemistry Chemistry 206 Advanced Organic Chemistry Lecture Number 33 Introduction to Organosilicon Chemistry ■ Silicon Bonding Considerations ■ The Silicon–Proton Analogy ■ C=O Addition of Organosilanes ■ Sigmatropic Rearrangements of Organosilanes ■ Anionic (Brook) Rearrangements ■ Peterson Olefination Reaction ■ Survey of Silicon (and related) Protecting Groups Masse, C. E.; Panek, J. S. "Diastereoselective reactions of chiral allyl- and allenylsilanes with activated C-X pi-bonds." Chem. Rev. 1995, 95, 1293-1316. Ager, D. J. "The Peterson olefination reaction." Org. Reactions 1990, 38, 1-224 Fleming, I.; Barbero, A.; Walter, D. "Stereochemical control in organic synthesis using silicon-containing compounds." Chem. Rev. 1997, 97, 2063-2192. (Web) Moser, W. H. "The Brook Rearrangement in Tandem Bond Formation Strategies," Tetrahedron 2001, 57, 2065-2084 (handout) Colvin, E. "Silicon in Organic Synthesis," Butterworths, 1981 KHMDS THF, -78 °C Calter, M. A. Ph. D. Thesis, Harvard University, 1993. 94% Bu3Sn Bu3Sn OMe TBSO Me OH OMe OH OTBS Explain what drives this rearrangement. TBS = Si Me Me CMe3 O TMS RO P OR R P O O RO OR SiR3 R P OTMS O RO OR The C=O addition illustrated in eq 1 proceeds while the carbon analogue (eq 2) does not. Explain (1) R H O O Me RO P OR R P O O RO OR Me R P OMe O RO OR (2) Me OLi Me3Si O X Me H H O OSiMe3 X Takeda, Org. Lett, 2000, 2, 903-1905 Provide a mechanism for the indicated transformation Problems to Contemplate Bois, et al. "SiliconTethered Reactions" Chem. Rev. 1995, 95, 1253-1277. (Handout) Carey & Sundberg, Advanced Organic Chemistry, 4th Ed. Part B Chapter 9, " C–C Bond Forming Rxns of Boron, Silicon & Tin", 595– 680