Ch 10 and 11 Chemistry of alcohols and thiols

chemically disuldes are generally produced with mild

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Unformatted text preview: 2 NaI + 2 H2O •  mechanistically: a series of SN2 reactions! R—S—H + –OH R—S– + H2O R—S– + I—I R—S—I + –I R—S– + R—S—I R—S—S—R + –I 10-60! Disulfides!   When thiols and disulfides are mixed, an equilibrium among them is rapidly established, governed by the leaving group capacity to leave:! SH + SH + SS SS SS SS + + SH SH 10-61! Designing Multistep Syntheses!   1. !Review the functional groups and carbon skeleton of the target.!   2. !Review the functional groups and carbon skeleton of the starting materials and evaluate how their skeletons might fit together to make the target compound.!   3. !Use the retrosynthetic approach to compare methods for assembling the carbon skeleton of the target compound to give the proper connectivity and functional group regiochemistry.!   4. !Bias your selection of retrosynthetic pathways towards the sequences that:! •  add less reactive groups earlier in a synthesis and more reactive groups later; and! •  utilize the lowest number of overall synthetic steps.!   5. !Summarize the complete synthesis in the forward direction, including all steps and all reagents, and check for errors/omissions.! 10-62! Example of Retrosynthetic Design! How could the following cyclic ether be prepared from the starting material shown?! ?? Br O Retrosynthetic analysis:! OH Br Br O open arrow indicates that you are working the problem backwards One possible solution:! Br 1) Hg(OAc)2, H2O 2) NaBH4 OH Na0 Br Et2O O 10-63! Synthesis Problem!   How would you synthesize! OH OH HO OH ! ! ! !from ! ! ! !?! 10-64! Retrosynthesis & Forward Synthesis!   Retrosynthetic Analysis:! OH ! !   HO OH O O OH O O Forward Synthesis:! O O 1) O3 OH OH NaBH4 2) Me2S O O HO OH 10-65! Design Multistep Syntheses for the Following Transformations! Br O O OH Br OH CH2Br + 10-66! Multistep Synthesis Examples!   How would you synthesize the target compound from the given starting materials?! O Br CD3I + CH3I + CH3 OH + CD3 Williamson ether synthesis! O CH3 Grignard reaction with ketone! CD3 Grignard reaction with epoxide! 10-67!...
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This note was uploaded on 01/27/2014 for the course BIOL 241 taught by Professor Henrychang during the Winter '10 term at Purdue University-West Lafayette.

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