Ethyl 8-Methyl-1,4-dioxa-spiro[4,5]decane-8-carboxylate

Synthesis

Ethyl 8-methyl-1,4-dioxaspiro[4.5]decane-8-carboxylate was synthesized as follows: n-butyllithium (n-BuLi, 1.6 eq.) was added slowly and dropwise to an anhydrous THF (1 M) solution of diisopropylamine (DIA, 1.2 eq.) over 20 min at 0 °C. The reaction mixture was stirred at 0 °C for 30 min and further cooled to -78 °C. Subsequently, a solution of ethyl 1,4-dioxaspiro[4.5]decane-8-carboxylate (1 eq.) in THF (1 M) was added slowly and dropwise over 30 minutes, followed by the addition of iodomethane (3 eq.). The reaction mixture was stirred at room temperature overnight. After completion of the reaction, the reaction mixture was diluted with brine and extracted with ethyl acetate. The organic layers were combined, washed with brine, dried over anhydrous sodium sulfate (Na2SO4) and filtered. The filtrate was concentrated to afford the target product ethyl 8-methyl-1,4-dioxaspiro[4.5]decane-8-carboxylate in 100% yield. The product was characterized by 1H NMR (400 MHz, CDCl3) with the following chemical shifts δ (ppm): 4.16 (q, J=7.1 Hz, 2H), 3.95 (s, 4H), 2.19-2.11 (m, 2H), 1.72-1.57 (m, 4H), 1.57-1.45 (m, 2H), 1.30-1.24 (m, 3H ), 1.20 (s, 3H).

References

[1] Patent: US2016/96841, 2016, A1. Location in patent: Paragraph 0332
[2] Patent: WO2018/13486, 2018, A1. Location in patent: Page/Page column 19
[3] Patent: US2009/253677, 2009, A1. Location in patent: Page/Page column 70
[4] Patent: CN105566324, 2016, A. Location in patent: Paragraph 0337; 0338; 0339; 0340
[5] Patent: US2009/275574, 2009, A1. Location in patent: Page/Page column 21