[Li+].[Cl-].P([CH2:11][C:12]#[N:13])(OCC)(OCC)=O.C1CCN2C(=NCCC2)CC1.[C:25]([O:29][C:30](=[O:42])[NH:31][C@H:32]([CH2:35][C:36]1[CH:41]=[CH:40][CH:39]=[CH:38][CH:37]=1)[CH:33]=O)([CH3:28])([CH3:27])[CH3:26]>C(#N)C>[C:25]([O:29][C:30](=[O:42])[NH:31][C@@H:32](/[CH:33]=[CH:11]/[C:12]#[N:13])[CH2:35][C:36]1[CH:37]=[CH:38][CH:39]=[CH:40][CH:41]=1)([CH3:28])([CH3:26])[CH3:27]
To a stirred suspension of LiCl (1.0 g, 24 mmol) in dry ACN (200 mL) under nitrogen at rt, was added (EtO)2POCH2CN (4.2 g, 24 mmol), DBU (3.0 g, 20 mmol) and compound 31d (5.0 g, 20 mmol). Almost all of the salt soon dissolved and the reaction completed in 1.5 h. The reaction was quenched with citric acid, and the mixture was extracted with EA three times. The combined organic layers were washed with brine and dried over anhydrous Na2SO4. After filtration, the filtrate was evaporated and the residue was purified by CC (hexane/EAc=5:1) to give compound 31e (4.2 g, 77% yield).
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