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TOSYLATES

The material here is from Chap. 12 and is repeated in Chap. 12 slides. TOSYLATES. TOSYLATES. p-TOLUENESULFONYL CHLORIDE. ALCOHOL. +. TsCl. +. TOSYL CHLORIDE. pyridine. ROTs. TOSYLATE ESTER. CONVERSION TO A TOSYLATE WITH TsCl AND PYRIDINE. Poor leaving group. TsCl. +. *. :. -.

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TOSYLATES

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  1. The material here is from Chap. 12 and is repeated in Chap. 12 slides. TOSYLATES

  2. TOSYLATES p-TOLUENESULFONYL CHLORIDE ALCOHOL + TsCl + TOSYL CHLORIDE pyridine ROTs TOSYLATE ESTER

  3. CONVERSION TO A TOSYLATE WITH TsCl AND PYRIDINE Poor leaving group TsCl .. + .. * : - Cl .. R-OTs pyridine * - + Cl Good leaving group for both SN1 and SN2 If the alcohol is chiral, the conversion to a tosylate retains configuration.

  4. EXAMPLE OF THE USE OF A TOSYLATE (R) (R) TsCl CH3-CH-OH CH3-CH-OTs pyridine Ph Ph RETENTION NaCN acetone SN2 INVERSION (S) CH3-CH-CN Ph

  5. EXPLANTION OF STEREOCHEMISTRY Same configuration as the starting alcohol. .. : pyridine NaCN acetone The first reaction step does not involve the carbon stereocenter - the atom oxygen reacts. This step is an SN2 reaction with inversion of configuration.

  6. BROSYLATES

  7. BROSYLATES WORK LIKE TOSYLATES p -bromobenzenesulfonyl chloride + “Brosyl Chloride” pyridine BsCl a p -bromobenzensulfonate “Brosylate” R-OBs a good leaving group

  8. ADENOSINE TRIPHOSPHATE ATP

  9. .. .. .. :O-R :O-R :O-R H H H R-O-H + ATP R-O-P or R-O-P-P or R-O-P-P-P triphosphate monophosphate diphosphate

  10. PHOSPHATES (MONO, DI, AND TRI) ARE GOOD LEAVING GROUPS FOR BOTH SN1 AND SN2 REACTIONS Nu: SN2 SN1 (ionization) .. .. .. .. : : : : : : : .. .. .. .. .. .. .. + .. : : : : .. .. .. .. .. .. .. : : : : : : : .. .. .. .. resonance stabilized ion

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