Uses
Tert-Butyl (1-(hydroxymethyl)cyclopropyl)carbamate could be converted into spirocyclopropanated analogues 14-CP and 14-CT of the insecticide Thiacloprid [1]. It can also be transformed into spirocyclopropanated analogs of Imidacloprid. This compound could be used to synthesize spirocyclopropanated five-membered ring analog 4-(3,5-Dichlorophenyl)-N-isopropyl-5-oxo-4,6-diazaspiro- [2.4]heptane-6-carboxamide[2].
Preparation
Tert-Butyl (1-(hydroxymethyl)cyclopropyl)carbamate can be synthesized in three steps (40 % overall yield) from N, Ndibenzyl-2-benzyloxyacetamide starting with its reductive cyclopropanation (the de Meijere variant of the so-called Kulinkovich reaction). It can also be prepared in 56 % overall yield by monohydrolysis of commercially available diethyl cyclopropane-1,1-dicarboxylate followed by Curtius degradation of the carboxylic acid residue and subsequent reduction of the ester moiety[1].
Synthesis
General procedure for the synthesis of (1-hydroxymethylcyclopropyl)-tert-butoxycarbonylamino acids from ethyl 1-(BOC-amino)cyclopropanecarboxylate: ethyl 1-((tert-butoxycarbonyl)amino)cyclopropanecarboxylate (4.31 g, 18.80 mmol) was dissolved in tetrahydrofuran (THF, 20 mL), and a 2M lithium borohydride (LiBH4) THF solution was slowly added dropwise ( 10.34 mL, 20.68 mmol), and the reaction mixture was stirred at room temperature overnight. Subsequently, a THF solution of 2M LiBH4 (5 mL, 10 mmol) was added additionally and stirring was continued at room temperature for 6 hours. Upon completion of the reaction, anhydrous sodium sulfate (Na2SO4, 15 g) and water (H2O, 10 mL) were added and the suspension was stirred at room temperature over the weekend. The suspension was filtered through a pad of sodium sulfate and the residue was washed with dichloromethane (DCM). The combined filtrates were concentrated under reduced pressure and the product was purified by column chromatography (silica gel, heptane/ethyl acetate, 1:1) to give 2.78 g of the target product in 79% yield.
References
[1] Brackmann F, et al. Synthesis of Spirocyclopropanated Analogues of Imidacloprid and Thiacloprid. European Journal of Organic Chemistry, 2005; 2005: 600-609.
[2] Brackmann F, et al. Synthesis of Spirocyclopropanated Analogues of Iprodione. European Journal of Organic Chemistry, 2005; 2005: 2250-2258.
