Reduction of 3-Trimethysilylcyclobutanone with KBH4; 3-(Trimethylsilyl)cyclobutanol
Submitted Apr 06, 2012, published Apr 06, 2012
Christopher Kelly (email@example.com
A contribution from
(99.9% trace metals basis, Sigma-Aldrich)
2-Propanol (anhydrous, 99.5%)
Diethyl Ether (CHROMASOLV®
, for HPLC, ≥99.9%, inhibitor-free, Sigma-Aldrich)
1 M NaOH soludtion
Sodium Sulfate (ACS reagent, ≥99.0%, anhydrous, granular, Sigma-Aldrich)
To a 500 mL round bottom flask equipped with stir bar and N2 inlet adaptor was added 12.13 g (0.08542 mol, 1 equiv) of 3-trimethylsilylcyclobutanone was added to a along with 250 mL of a 95:5 2-propanol : water solution(0.353 M in the cyclobutanone). KBH4 (7.01g, 0.1281 mol, 1.5 molar equiv) was added to the flask via a ground glass funnela,b,c and the solution reaction mixture was placed under a N2 atmosphere. Reaction progress was monitored by GC-MS and, after about 1.5 hr, the reaction was complete.
2-Propanol was removed via rotary evaporation until a cloudy slurry remained. The slurry was diluted with diethyl ether (≈ 200 mL) and was transferred to a 1000 mL separatory funnel. The organic layer was washed with aqueous NaOH (100 mL, 1 M) to remove the boric acid byproduct. The two layers were separated and the aqueous layer was then re-extracted with ether (3X 100 mL). The organic layers were combined and washed with 150 mL brine. The organic layer was dried with Na2SO4 and the volatiles were removed via rotary evaporation under aspirator vacuum in a heated water bath (70oC). A cloudy oil remained and was further purified by vacuum distillation (bp 80 oC at 30 mm Hg) giving 3-trimethylsilylcyclobutanol as a colorless oil (9.13g, 74.2%). Ratio of the cis to trans isomers was determined to be 93:7 by both NMR and GC-MS.2
Data is for the major cis isomer unless otherwise indicated:
1H-NMR (CDCl3, 300 MHz) δ -0.03 (9H, s), 0.93-1.06 (1H, m), 1.59-1.71 (2H, m), 2.10 (1H, d, OH, J = 7.0 Hz), 2.21-2.32 (2H, m); trans δ -0.05 (9H, s, Me3Si) – other peaks for the trans isomer were too small to be seen or were obscured by the other isomer
13C NMR (CDCl3 75 MHz) δ -3.35 (CH3), 11.59 (CH), 35.00 (CH2), 67.11 (CH). trans δ -3.20 (CH3), 11.21 (CH), 34.16 (CH2), 66.90 (CH)
GC-MS (EI) 144 ([M]+, 0.33%), 143 ([M-H]+, 0.59%), 129 ([M-CH3]+, 32.9%) 116 (4.3%), 101 (7.8%), 85 (18.1%), 75 (78.4 %), 73 (100%), 59(15.0%), 54 (24.0%), 45 (24.0%) 43 (20.7%).
1. S. Kobayashi, H. Miyamura, R. Akiyama, T. Ishida, J. Am. Chem. Soc. 2005, 127, 9251-9254.
2. X. Creary, E. D. Kochly, J. Org. Chem. 2009, 74, 9044.
1H NMR (cyclobutanol hnmr.jpg)
13C NMR (cyclobutanol c13 nmr.jpg)
Keywords: alcohols, Alkanes, Borohydride Reduction, Organosilicon Chemistry, reduction, Small Ring Systems