Ammonium Chloride → (4R,5S,6S)-1,1-diisopropoxy-5-hydroxy-2,2,4,6-tetramethyl-8-nonen-3-one

HRID 348235Notes

Reaction equation

C([O:4][CH:5]([O:13][CH:14]([CH3:16])[CH3:15])[C:6]([CH3:12])([CH3:11])[C:7](=[O:10])[CH2:8][CH3:9])(C)C.C([N-][CH:21]([CH3:23])[CH3:22])(C)C.[Li+].[CH3:25][C@@H:26]([CH2:29][CH:30]=[CH2:31])[CH:27]=[O:28].[NH4+].[Cl-]>C1COCC1.C(Cl)Cl>[CH:14]([O:13][CH:5]([O:4][CH:21]([CH3:22])[CH3:23])[C:6]([CH3:11])([CH3:12])[C:7](=[O:10])[C@H:8]([CH3:9])[C@@H:27]([OH:28])[C@@H:26]([CH3:25])[CH2:29][CH:30]=[CH2:31])([CH3:15])[CH3:16]

Participants

Conditions

Temperature: -78 °C

Procedure

A solution of 1,1-diisopropoxy-2,2-dimethyl-3-pentanone (3.29 g) in 15 mL of THF is added slowly to a solution of lithium diisopropylamide (15.7 mmol) in 20 mL of THF cooled to −78° C., the mixture is stirred for 30 minutes, warmed to −40° C. and stirred for 30 minutes, then recooled to −78° C. A solution of (2S)-2-methyl-4-pentenal (16.36 mmol) in 2 mL of CH2Cl2 is added and the mixture is stirred for 1 hour at −78° C. Saturated aq. NH4Cl is added and the mixture is warmed to ambient temperature and extracted with ethyl acetate. The extract is dried over Na2SO4, filtered, and evaporated. The residue is purified by silica gel chromatography (2% ethyl acetate/hexanes) to separate the two diastereomeric products.

Workup

temperaturewarmed to −40° C.
stirringstirred for 30 minutes
customrecooled to −78° C
stirringthe mixture is stirred for 1 hour at −78° C
temperaturethe mixture is warmed to ambient temperature
extractionextracted with ethyl acetate
dry with materialThe extract is dried over Na2SO4
filtrationfiltered
customevaporated
customThe residue is purified by silica gel chromatography (2% ethyl acetate/hexanes)
customto separate the two diastereomeric products

Sources & evidence

ORD record: ord-c2dea00e9c53444ba8aa14cf3a136fbe
Source dataset: uspto-grants-2007_02
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US07176235B2

Reaction notes

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