Réaction #57069

Équation de réaction

26

5,6-Dibromo-4,7-dimethyl-1,4-epoxy-1,4-dihydronapthalene

trifluoroethanol

methanol

→

29

Rendement 79.0%

(1S,2S)-6,7-Dibromo-2-methoxy-5,8-dimethyl-1,2-dihydronaphthalen-1-ol

Rendement 79.0%

Conditions de réaction

Traitement

1. 1
   AutreTo a flame dried round bottom flask
2. 2
   TempératureThe mixture was heated
3. 3
   Températureto reflux for 20 hours
4. 4
   AutreThe solvents were then removed in vacuo
5. 5
   AutreThe resulting solid was purified by flash chromatography (50% ethyl acetate in hexanes)

Mode opératoire

To a flame dried round bottom flask, [Rh(COD)Cl]2 (1.5 mg, 0.0029 mmol), (R)—(S)-PPF-PtBu2 (3.2 mg, 0.0059 mmol) and 26 (195 mg, 0.59 mmol) were added followed by addition of trifluoroethanol (1.0 mL) and methanol (1.0 mL). The mixture was heated to reflux for 20 hours. The solvents were then removed in vacuo. The resulting solid was purified by flash chromatography (50% ethyl acetate in hexanes) to give 29 as a white crystalline solid (171.6 mg, 79%). The ee was determined to be 97% using HPLC analysis on a CHIRALCEL OD column, λ=486 nm. Retention times in 4% isopropanol in hexanes were 16.8 min (major) and 19.3 min. Rf=0.39 on silica gel (50% ethyl acetate:hexanes); mp 114-116° (Et2O); [α]25D=−197.1° (c=10.0, CHCl3); IR (KBr, cm−1) 3349 (s), 2901 (m), 1700 (w), 1532 (w), 1404 (m), 1258 (m), 1081 (s), 936 (s); 1H NMR (400 MHz, CDCl3) δ 6.96-6.93 (1H, m), 6.23-6.19 (1H, m), 4.89 (1H, s), 3.96-3.90 (1H, m), 3.38-3.35 (3H, m), 2.61-2.57 (3H, m), 2.54 (3H, s), 1.82-1.54 (1H, m); 13C NMR (400 MHz, CDCl3) δ 137.3, 134.4, 133.2, 129.7, 129.5, 129.0, 128.1, 125.3, 75.3, 66.6, 56.6, 21.0, 20.6. HRMS calcd for C13H16O2Br2 (M+): 361.9518. Found: 361.9335.

Source