Diisopropylamine → 1-tert-Butyl 4-ethyl 4-(prop-2-en-1-yl)piperidine-1,4-dicarboxylate

Temperature

-78 °C

In a 250-mL RBF was weighed 6.1 g (60 mmol) of diisopropylamine and dissolved in THF. This solution was cooled to −78° C. To this was added 24 mL of 2.5 M (60 mmol) of butyllithium in hexane and stirred for 15 min, warmed up to 0° C. for 20 min, re-cooled to −78° C. To this was added piperidine-1,4-dicarboxylic acid 1-tert-butyl ester 4-ethyl ester (12.87 g, 50 mmol) in THF (10 mL). There was almost no color change. This was stirred at −78° C. for 45 min. Then, a mixture of 5 g of HMPA and 10.92 g of allyl iodide was added via cannula. The solution was still clear, very light in yellow. This mixture was stirred at −78° C. for 20 min, then, the dry ice bath was removed and the stirring was continued to allow the reaction mixture warm to r.t. over 40 min. The reaction mixture was poured into ice (˜50 g), sat'd NH4Cl aq. (50 mL) and ether (50 mL). The two layers were separated, the aqueous layer was extracted with ether (3×50 mL). The combined organic layers were washed with brine, dried (K2CO3), filtered, and concentrated in vacuo to obtain 15 g (100%) of the title compound as a yellow liquid,

1. temperaturewarmed up to 0° C. for 20 min
2. temperaturere-cooled to −78° C
3. stirringThis was stirred at −78° C. for 45 min
4. additionwas added via cannula
5. stirringThis mixture was stirred at −78° C. for 20 min
6. customthe dry ice bath was removed
7. temperaturewarm to r.t. over 40 min
8. additionThe reaction mixture was poured into ice (˜50 g)
9. customThe two layers were separated
10. extractionthe aqueous layer was extracted with ether (3×50 mL)
11. washThe combined organic layers were washed with brine
12. dry with materialdried (K2CO3)
13. filtrationfiltered
14. concentrationconcentrated in vacuo

ORD record

ord-a5a7ed5293fc4742bd81fbb4eefe906b

Source dataset

uspto-grants-2012_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08227481B2