2. I. Metal Based Reagents. II Non-Metal Based Reagents III. Epoxidations Oxidations

3. I. Metal Based Reagents 1. Chromium Reagents 2. Manganese Reagents. 3. Silver 4. Ruthenium 5. other metals II Non-Metal Based Reagents 1. Activated DMSO 2. Peroxides and Peracids 3. Oxygen/ ozone 4. others III. Epoxidations Oxidations Lec. 3

4. Metal Based Reagents Chromium Reagents - Cr(VI) based - exact structure depends on solvent and pH - Mechanism: formation of chromate ester intermediate Westheimer et al. Chem Rev. 1949, 45, 419 ; JACS 1951, 73, 65. Lec. 3

5. Jones Reagent (H 2 CrO 4, H 2 Cr 2 O 7, K 2 Cr 2 O 7 ) J. Chem. Soc. 1946 39; Org. Syn. Col. Vol. V, 1973, 310. CrO 3 + H 2 O H 2 CrO 4 (aqueous solution) 2°- alcohols are oxidized to ketones Lec. 3

6. saturated 1° alcohols are oxidized to carboxylic acids.

7. Lec. 3 Acidic media not a good method for H + sensitive gp. and compounds Acidic media not a good method for H + sensitive gp. and compounds

8. Collins Oxidation (CrO 3 2pyridine) TL 1969, 336 - CrO 3 (anhydrous) + pyridine (anhydrous) CrO 3 2pyridine -1° and 2° alcohols are oxidized to aldehydes and ketones in non- aqueous solution (CH 2 Cl 2 ) without over-oxidation. * - Collins reagent can be prepared and isolated or generated in situ. Isolation of the reagent often leads to improved yields. - Useful for the oxidation of H + sensitive compounds. - not particularly basic or acidic - must use a large excess of the reagent. Collins Oxidation (CrO 3 2pyridine) TL 1969, 336 - CrO 3 (anhydrous) + pyridine (anhydrous) CrO 3 2pyridine -1° and 2° alcohols are oxidized to aldehydes and ketones in non- aqueous solution (CH 2 Cl 2 ) without over-oxidation. * - Collins reagent can be prepared and isolated or generated in situ. Isolation of the reagent often leads to improved yields. - Useful for the oxidation of H + sensitive compounds. - not particularly basic or acidic - must use a large excess of the reagent. Lec. 3

10. Pyridinium ChloroChromate (PCC, Corey-Suggs Oxidation) TL 1975 2647 Synthesis 1982, 245 (review) CrO 3 + 6M HCl + pyridine pyH+CrO 3 Cl - - Reagent can be used in close to stoichiometric amounts w/ substrate - PCC is slightly acidic but can be buffered w/ NaOAc Pyridinium ChloroChromate (PCC, Corey-Suggs Oxidation) TL 1975 2647 Synthesis 1982, 245 (review) CrO 3 + 6M HCl + pyridine pyH+CrO 3 Cl - - Reagent can be used in close to stoichiometric amounts w/ substrate - PCC is slightly acidic but can be buffered w/ NaOAc Lec. 3

11. Allylic Hydrogen

13. Lec. 3

14. Pyridinium Dichromate (PDC, Corey- Schmidt Oxidation

15. Lec. 3