Acetic Acid → (S)-2-ethynyl-3,4-dihydro-2,5,7,8-tetramethyl-2H-1-benzopyran-6-ol

HRID 1199247

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

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

filtrationfiltered
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-e3b811eee45546ad9bb7b4ad272e8caa
Source dataset: uspto-grants-1990_02
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US04898962

Linked notes

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