Reaction #1702034

Reaction equation

HCl

diisopropylethylamine

acetyl bromide

5

3-Methoxydodecanal

AlMe3

→

6

Yield 77.3%

(4R)-4-((2RS)-2-Methoxyundecyl)oxetan-2-one

Yield 77.3%

Solvents

CH2Cl2

CH2Cl2

Conditions

Workup

1. 1
   Temperaturecooled to −45° C.
2. 2
   workup.STIRRINGThe resulting pale yellow solution was stirred for 14 h at −45° C.
3. 3
   Temperaturewarmed to rt
4. 4
   workup.ADDITIONpoured into a separatory funnel
5. 5
   WashThe organic layer was washed with saturated NaHCO3, brine
6. 6
   Dryingdried (Na2SO4)
7. 7
   OtherThe solvent was removed in vacuo
8. 8
   Otherthe yellow oily product was purified by chromatography on SiO2 (4% EtOAc/hexanes to 6% EtOAc/hexanes)

Procedure

A solution of N,N′-(1R,1′R)-1,1′-(benzylazanediyl)bis(2-methylpropane-1,1-diyl)bis(1,1,1-trifluoromethanesulfonamide) (81.2 mg, 0.15 mmol, 30 mol %) in CH2Cl2 (1 mL) was treated at rt under N2 slowly with a solution of AlMe3 (10.8 mg, 0.15 mmol) in CH2Cl2 (0.5 mL). The mixture was stirred at room temperature (rt) for 2 h, cooled to −45° C. and treated sequentially with diisopropylethylamine (11 mg, 1.7 equiv), acetyl bromide (117 mg, 1.9 equiv) and 5 (107 mg, 0.500 mmol, 1.0 equiv). The resulting pale yellow solution was stirred for 14 h at −45° C., warmed to rt, and poured into a separatory funnel containing 0.1 N HCl (10) mL). The organic layer was washed with saturated NaHCO3, brine, and dried (Na2SO4). The solvent was removed in vacuo and the yellow oily product was purified by chromatography on SiO2 (4% EtOAc/hexanes to 6% EtOAc/hexanes) to give 6 (99.1 mg, 77%) as a colorless oil: 1H NMR (CDCl3) 4.8-4.65 (m, 1H), 3.60-3.50 (m, 1H), 3.3-3.2 (m, 1H), 3.35, 3.32 (2s, 3H), 3.22-3.08 (m, 1H), 2.18-1.82 (m, 2H) 1.65-1.35 (m, 2H), 1.35-1.20 (m, 14H), 0.90-0.80 (m, 3H).

Source