β,β-Carotene, 15,15′-didehydro- → 15-cis-β-Carotene

HRID 1580424Notes

Reaction equation

HRID 1580424 reaction equation
[CH3:1][C:2]1[CH2:7][CH2:6][CH2:5][C:4]([CH3:9])([CH3:8])[C:3]=1/[CH:10]=[CH:11]/[C:12](/[CH3:40])=[CH:13]/[CH:14]=[CH:15]/[C:16](/[CH3:39])=[CH:17]/[C:18]#[C:19]/[CH:20]=[C:21](\[CH3:38])/[CH:22]=[CH:23]/[CH:24]=[C:25](\[CH3:37])/[CH:26]=[CH:27]/[C:28]1[C:33]([CH3:35])([CH3:34])[CH2:32][CH2:31][CH2:30][C:29]=1[CH3:36]>[Pd].CC([O-])=O.CC([O-])=O.[Pb+2]>[CH3:36][C:29]1[CH2:30][CH2:31][CH2:32][C:33]([CH3:34])([CH3:35])[C:28]=1/[CH:27]=[CH:26]/[C:25](/[CH3:37])=[CH:24]/[CH:23]=[CH:22]/[C:21](/[CH3:38])=[CH:20]/[CH:19]=[CH:18]\[CH:17]=[C:16](/[CH3:39])\[CH:15]=[CH:14]\[CH:13]=[C:12](/[CH3:40])\[CH:11]=[CH:10]\[C:3]1[C:4]([CH3:9])([CH3:8])[CH2:5][CH2:6][CH2:7][C:2]=1[CH3:1]

Participants

3

Reactant 1

HCID 21598333β,β-Carotene, 15,15′-didehydro-

Product 1

HCID 1230563915-cis-β-Carotene

Reagents, catalysts & solvents 1

HCID 131709914Lindlars catalystCatalyst

Procedure

Two moles of β-C19 -aldehyde (I) are condensed with acetylenedimagnesium bromide to give the C40 -diol (II). The C40 -diol is converted into 15,15' didehydro-β-carotene (III) by allylic rearrangement with simultaneous dehydration. The product is partially hydrogenated over Lindlar catalyst to give mainly 15-cis-β-carotene (IV) which is isomerized to all-trans-β-carotene by treatment in high boiling petroleum ether. While several methods of obtaining β-carotene from vitamin A have been proposed, the conditions required in these methods are extreme, the reagents are expensive, and, worst of all, the yields are low.

Sources & evidence

ORD record
ord-b2aad2928f8b4aa287a29144ad59054e
Source dataset
uspto-grants-1976_01
Patent number
US03932546

Reaction notes

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