9-Borabicyclo(3.3.1)nonane → 1,4-Dioxaspiro(4.5)dec-7-ene

A solution of 4.50 g (20 mmoles) of 4-morpholino-3-cyclohexene-1-one ethylene ketal in 10 ml of tetrahydrofuran (THF) is added to 2.44 g (20 mmoles) of solid 9-BBN. A suspension results which becomes clear after stirring for 6 hours at room temperature. The THF is removed under reduced pressure (20 Torr) and 2 ml of methanol is added to the remaining solid. An exothermic reaction is initiated by gentle warming and results in a clear solution which is stirred. The stirring is stopped and the mixture is cooled slowly to room temperature to crystallize the by-product, B-(morpholino)-9-BBN methanol complex. The solid is triturated with n-pentane (3×30 ml) and the combined pentane layers are washed successively with water (3×10 ml), 3N sodium hydroxide (3×6 ml) and water (2×10 ml). The pentane solution is dried and the pentane is evaporated under reduced pressure (20 Torr). The residue is purified by distillation to give 2.10 g (75 percent yield based on 4-morpholino-3-cyclohexene-1-one ethylene ketal) of 3-cyclohexene-1-one ethylene ketal, boiling point, 82° C.-84° C. at 20 Torr.

1. customA suspension results which
2. customThe THF is removed under reduced pressure (20 Torr) and 2 ml of methanol
3. additionis added to the remaining solid
4. customAn exothermic reaction
5. temperatureby gentle warming
6. customresults in a clear solution which
7. stirringis stirred
8. temperaturethe mixture is cooled slowly to room temperature
9. customto crystallize the by-product, B-(morpholino)-9-BBN methanol complex
10. customThe solid is triturated with n-pentane (3×30 ml)
11. washthe combined pentane layers are washed successively with water (3×10 ml), 3N sodium hydroxide (3×6 ml) and water (2×10 ml)
12. dry with materialThe pentane solution is dried
13. customthe pentane is evaporated under reduced pressure (20 Torr)
14. distillationThe residue is purified by distillation

ORD record

ord-60685b29f5d44fc780f3fefb509cd75e

Source dataset

uspto-grants-1990_01

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04895996