[CH3:1][C:2]([CH3:22])([O:4][C:5]([NH:7][C@@H:8]([CH2:15][CH:16]1[CH2:21][CH2:20][CH2:19][CH2:18][CH2:17]1)[C:9](N(OC)C)=[O:10])=[O:6])[CH3:3].[H-].[Al+3].[Li+].[H-].[H-].[H-].O1CCCC1.Cl>C(OCC)C>[CH3:3][C:2]([CH3:22])([O:4][C:5]([NH:7][C@@H:8]([CH2:15][CH:16]1[CH2:17][CH2:18][CH2:19][CH2:20][CH2:21]1)[CH:9]=[O:10])=[O:6])[CH3:1](S)-α-[[(1,1-Dimethylethoxy)carbonyl]amino]-N-methoxy-N -methylcyclohexanepropanamide (55.3 g., 175.9 mmole, 1 eq.) was dissolved in diethyl ether (1760 ml., 0.1M) and cooled in an ice bath. A solution of lithium aluminum hydride in tetrahydrofuran (193 ml., 193 mmole, 1.1 eq., 1M in tetrahydrofuran) was added dropwise over 90 minutes. After 75 minutes, a 1N HCl solution (1 l.) was added cautiously and slowly. The cooling bath was removed and the mixture was stirred for 2 hours. The layers were separated and the aqueous layer was reextracted with ether (2×400 ml.). The combined ether layers were dried (MgSO4) and freed of solvent in vacuo leaving a viscous oil (46.47 g.). This was chromatographed on silica gel (500 g., Merck) which was packed in hexane. The aldehyde was eluted with ether:hexane (1:1) to give (S)-α-[[(1,1dimethylethoxy)carbonyl]amino]cyclohexanepropanal.
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