107575-60-0Relevant articles and documents
Preparation of PQQ in the kg Scale
Martin, Pierre,Steiner, Eginhard,Auer, Kurt,Winkler, Tammo
, p. 1667 - 1673 (1993)
The improvement of the PQQ synthesis according to the method of Corey and Tramontano allows the preparation of the triester of this cofactor in the kg scale with an overall yield of 13percent (average 78percent per step), without a bottleneck in the sequence and with crystalline, analytically pure intermediates.The new purification of free PQQ from conc.H2SO4 is remarkable with respect to the application as well as to the stability of this natural product.
SYNTHESIS OF PYRROLOQUINOLINE QUINONE (PQQ)
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Page/Page column 9; 15; 1/6, (2010/11/24)
The invention relates to a novel nine step process for synthesizing PQQ (methoxatin). This process is efficient and reliably provides PQQ in excellent purity and high yield.
Method for dyeing keratinous fibres using an aminoindole in combination with a quinone derivative
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, (2008/06/13)
Method for dyeing keratinous fibres, characterized in that at least one composition (A) containing at least one aminoindole in a medium appropriate for dyeing is applied to these fibres, the application of the composition (A) being preceded or followed by the application of a composition (B) containing, in a medium appropriate for dyeing, at least one quinone derivative chosen from ortho- or para-benzoquinones, ortho- or para-benzoquinone monoimines or diimines, 1,2- or 1,4-naphthoquinones, ortho- or para-benzoquinone sulphonimides, α,ω-alkylene-bis-1,4-benzoquinones, or 1,2- or 1,4-naphthoquinone monoimines or diimines, the aminoindoles and the quinone derivatives being chosen such that the difference in redox potential ΔE between the redox potential Ei of the aminoindoles, determined at pH 7 in a phosphate medium on a vitreous carbon electrode by voltametry, and the redox potential Eq of the quinone derivative, determined at pH 7 in a phosphate medium by polarography on a mercury electrode relative to the saturated calomel electrode, in such that