Acetic Acid → (S)-2-ethynyl-3,4-dihydro-2,5,7,8-tetramethyl-2H-1-benzopyran-6-ol
Reaction equation
C(O[C@@:5]([CH3:21])([C:19]#[CH:20])[CH2:6][CH2:7][C:8]1[C:9](=[O:18])[C:10]([CH3:17])=[C:11]([CH3:16])[C:12](=[O:15])[C:13]=1[CH3:14])(=O)C.C(O)(=O)C>C(Cl)Cl.[Zn]>[C:19]([C@:5]1([CH3:21])[CH2:6][CH2:7][C:8]2[C:13]([CH3:14])=[C:12]([OH:15])[C:11]([CH3:16])=[C:10]([CH3:17])[C:9]=2[O:18]1)#[CH:20]Participants
5
Reactant 2
Product 1
Reagents, catalysts & solvents 2
Conditions
- Temperature
- 4 °C
Procedure
A solution of 285 mg (0.99 mmol) of (R)-2-[3-(acetyloxy) 3-methyl-4-pentynyl]-3,5,6-trimethyl-2,5-cyclohexadiene-1,4-dione in 4 mL of CH2Cl2 was stirred with 250 mg of Zn dust, and 250 mg of glacial acetic acid. The reaction mixture was stirred at 4° C. under argon for 50 min. then filtered. It was worked up with CH2Cl2 as described above. The crude hydroquinone acetate was taken into 6 mL of CH2Cl2 and treated with 20 mg of AgClO4 ·H2O as described above to give 124 mg of crude product after workup, and purification by flash chromatography. Crystallization of this material from toluene-hexane (1:1) at -15° C. gave 57 mg of (S)-2-ethynyl-3,4-dihydro-2,5,7,8-tetramethyl-2H-1-benzopyran-6-ol: [α]D25 +20.20°, (c 1.3, CHCl3).
Workup
- filtrationthen filtered
- additiontreated with 20 mg of AgClO4 ·H2O
- customto give 124 mg of crude product
- customafter workup, and purification by flash chromatography
- customCrystallization of this material from toluene-hexane (1:1) at -15° C.
Sources & evidence
- ORD record
- ord-f2d5e3af4e014a908249a6be66c0cf40
- Source dataset
- uspto-grants-1990_02
- Patent number
- US04898953
Reaction notes
Loading…