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. 2022 Feb 1;13(8):2378–2384. doi: 10.1039/d2sc00113f

Optimization of the crossed [2+2] photocycloaddition of 2-(allyloxy)cyclohex-2-enone (4a) to product 5a catalyzed by chiral Lewis acid 6.

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Entrya Solvent λ [nm] Conv.b [%] Yieldc [%] % eed
1 MeCN 425 2
2 PhMe 425 11 11 15
3 THF 425 11 11 20
4 CH2Cl2 425 85 22 87
5 DCE 425 83 61 91
6e DCE 425 91 68 87
7f DCE 425 95 86 85
8 DCE 437 93 86 92
9e DCE 437 73 55 90
10g DCE 437 79 64 94
11h DCE 437 89 78 87
12i DCE 437 72 70 87
a

All reactions were performed under anaerobic conditions employing a light emitting diode (LED) in a previously described set-up.19

b

The conversion (conv.) was determined by NMR analysis.

c

All yields refer to isolated material.

d

Enantiomeric excess (ee) as determined by GLC analysis on a chiral stationary phase.

e

The reaction was performed in the presence of air.

f

The reaction time was 24 hours.

g

The catalyst loading was 4 mol%.

h

The reaction was performed at 0 °C.

i

The substrate concentration was 4 mM.