Sulfuric Acid → 2-(2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl)-2-methylhex-5-en-3-one

HRID 1003152Notes

Reaction equation

HRID 1003152 reaction equation
[Cr](O)(O)(=O)=O.[Cr](O[Cr]([O-])(=O)=O)([O-])(=O)=O.[Na+].[Na+].S(=O)(=O)(O)O.[CH3:22][C:23]1[O:28][CH2:27][N:26]([C:29]([CH3:36])([CH:31]([OH:35])[CH2:32][CH:33]=[CH2:34])[CH3:30])[C:25](=[O:37])[C:24]=1[C:38]1[CH:43]=[CH:42][CH:41]=[CH:40][CH:39]=1>O.CCOCC>[CH3:22][C:23]1[O:28][CH2:27][N:26]([C:29]([CH3:30])([C:31](=[O:35])[CH2:32][CH:33]=[CH2:34])[CH3:36])[C:25](=[O:37])[C:24]=1[C:38]1[CH:43]=[CH:42][CH:41]=[CH:40][CH:39]=1

Participants

7

Reactant 4

HCID 1118Sulfuric AcidHCID 24425Chromic AcidHCID 25408Sodium DichromateHCID 22118283HCID 22118283, compound

Product 1

HCID 187955282-(2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl)-2-methylhex-5-en-3-oneYield 12.1%

Reagents, catalysts & solvents 2

HCID 962WaterSolvent2×HCID 3283Diethyl EtherSolvent

Procedure

Chromic acid [1.7 ml of a solution prepared by the addition of a solution of sodium dichromate (0.4 g) in water (1.2 ml) to concentrated sulphuric acid (0.54 ml) and diluted to 2 ml with water] was added dropwise at 25° C. to a stirred solution of 2-(2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl)-2-methylhex-5-ene-3-ol (1.0 g) in ether. After 18 hours the ether layer was separated, washed with sodium bicarbonate solution (2N) and with brine, dried (magnesium sulphate) and evaporated. The residue was purified by dry column chromatography on silica gel eluting with dichloromethane, to give 2-(2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl)-2-methylhex-5-en-3-one (Compound 7, 0.12 g) as a yellow oil, NMR 1H δ1.4(s,6H), 1.88(s,3H), 3.22(d,2H), 5.05(m,2H), 5.22(s,2H), 5.9(m.1H), 7.2-7.35(m,5H).

Workup

  1. customAfter 18 hours the ether layer was separated
  2. washwashed with sodium bicarbonate solution (2N) and with brine
  3. dry with materialdried (magnesium sulphate)
  4. customevaporated
  5. customThe residue was purified
  6. dry with materialby dry column chromatography on silica gel eluting with dichloromethane

Sources & evidence

ORD record
ord-cab4c3cf42fa43b1aa8b6df939a31d21
Source dataset
uspto-grants-2000_04
Patent number
US06046135

Reaction notes

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