Reaction #48279

Reaction equation

4-(2,2-dimethoxyethyl)hepta-1,6-dien-4-ol

tetrakis-(hydroxymethyl)phosphonium chloride

→

title compound

2,2-dimethoxyethylcyclopent-3-enol

Solvents

DCM

water

isopropanol

NaOH

Conditions

Workup

1. 1
   OtherDry argon was bubbled through the solution for 30 minutes
2. 2
   workup.STIRRINGstirred for 15 hours
3. 3
   workup.ADDITIONpoured into a seperatory funnel
4. 4
   OtherThe DCM layer was separated
5. 5
   Extractionthe aqueous was extracted with DCM (3×100 mL)
6. 6
   ConcentrationThe combined organics were concentrated to a dark oil which
7. 7
   Otherwas purified by flash chromatography on a 330 g ISCO column
8. 8
   Washeluting by gradient hexanes to 20% EtOAc/ hexanes over a 50 minute period

Procedure

A solution of 4-(2,2-dimethoxyethyl)hepta-1,6-dien-4-ol (28 g, 140 mmol) in DCM (2L) was charged to a 3 L RB flask. Dry argon was bubbled through the solution for 30 minutes. Grubbs second generation catalyst (5.9 g, 7.0 mmol) was added and the reaction was allowed to stir under argon for 15 hours. The reaction was quenched with a solution of tetrakis-(hydroxymethyl)phosphonium chloride (27 g, 140 mmol) in isopropanol (200 mL) and 10 N NaOH (14 mL), and stirred for 15 hours. The reaction was diluted with water (1 L) and poured into a seperatory funnel. The DCM layer was separated and the aqueous was extracted with DCM (3×100 mL). The combined organics were concentrated to a dark oil which was purified by flash chromatography on a 330 g ISCO column eluting by gradient hexanes to 20% EtOAc/ hexanes over a 50 minute period. Product fractions were combined to afford the title compound.

Source