8H-Indeno[1,2-d]oxazole, 2,2'-(1-methyl-2-phenylethylidene)bis[3a,8a-dihydro-, (3aS,3'aS,8aR,8'aR)- synthesis

Yield:1379763-05-9 87%

Reaction Conditions:

Stage #1: C₂₂H₂₀N₂O₂with tert.-butyl lithium in tetrahydrofuran at -78;
Stage #2: benzyl bromide in tetrahydrofuran at -78 - 20; for 36.3333 h;

Steps:

4.2. Typical procedure for the synthesis of chiral ligands

General procedure: To a solution of Inda-bisoxazoline (0.65 g, 1.9 mmol) in dried THF (30 mL) was added dropwise t-BuLi (2 mL, 1.3 M in THF, 2.6 mmol) within 15-20 min at -78 °C. The resulting yellow solution was stirred for 1 h at the same temperature, then a solution of 2-chloromethyl oxazoline or benzyl bromide (2.8 mmol) in THF (10 mL) was added dropwise at -78 °C over 20 min. The mixture was slowly warmed to room temperature and kept stirring for a further 36 h. The solvent was removed and the residue was diluted with CH₂Cl₂ (100 mL), then washed with H₂O (20 mL). The aqueous layer was extracted with CH₂Cl₂ (2×20 mL), and the combined organic phases were dried over Na₂SO₄, filtered, and concentrated. The residue was purified by flash chromatography (petroleum ether/acetone=10/1) to afford the desired product.

References:

Chen, Jiang-Hua;Liao, Sai-Hu;Sun, Xiu-Li;Shen, Qi;Tang, Yong [Tetrahedron,2012,vol. 68,# 25,p. 5042 - 5045] Location in patent:supporting information; experimental part