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. 2021 Apr 14;12(20):7066–7072. doi: 10.1039/d1sc01349a

Optimization of the propellylation/borylation reaction. [1.1.1]propellane (1, 1.4 equiv.), reaction concentration = 0.2 M.

graphic file with name d1sc01349a-u1.jpg
Entry Base (equiv.) Bpin source (equiv.) Time (h) % 7aa % 4aa % 5a : 9a : 7a′a
1b LiN(SiMe3)2 (2) B2pin2 (2) 4 43 0 13 : 0 : 5
2b LiN(SiMe3)2 (1) B2pin2 (2) 7 55 0 18 : 0 : 6
3b NaN(SiMe3)2 (2) B2pin2 (2) 24 25 0 70 : 0 : 4
4b,c n-BuLi (1.1) B2pin2 (2) 2 49 6 0 : n/d : 4
5b n-BuLi (1.1) iPrOBpin (1.1) 2 33 6 10 : 27 : 2
6b n-BuLi (1.1) iPrOBpin (5) 2 62 19 5 : 1 : 6
7 n-BuLi (1.1) iPrOBpin (5) 2 73 8 0 : 0 : 6
8 LDA (1.1) iPrOBpin (5) 16 74 [61%] 14 0 : 0 : 7
9d LDA (1.1) iPrOBpin (5) 2 60 6 0 : 0 : 3
a

Determined by 1H NMR analysis of the crude reaction mixture using CH2Br2 as an internal standard.

b

Base added at room temperature.

c

1H NMR spectrum of the crude reaction mixture was too complex to accurately quantify 9a and 4a.

d

Reaction initiated at −78 °C and warmed to 50 °C.