Degussa Aktiengesellschaft

Forschungszentrum Juelich Gmbh

Karl-Heinz Drauz

Gunter Prescher

Gebhard Ritter

Axel Kleeman

Christian Wandrey

Andreas Bommarius

Guenter Knaup

Alexander Schwarz

Andreas Fischer

Protected and unprotected di- or oligopeptides are synthesized by reacting an N-terminally protected .alpha.-amino acid alkyl ester or peptide alkyl ester of the formula X--E--R.sup.1 with an amino acid or a di- or oligopeptide or a derivative thereof of the formula H.sub.2 N--Q--R.sup.2 in aqueous solution in the presence of a hydrolase, and, removing protective groups from the reaction product separated from the reaction mixture, where E is the residue of an .alpha.-amino acid or of a di- or oligopeptide, R.sup.1 is lower alkyl and X is a group which carries a charge or is polar at the pH values used for the reaction and which increases the solubility by a factor &gt;5 compared with compounds wherein X=H, Q is the residue of an amino acid or of a di- or oligopeptide, and R.sup.2 is an optionally esterified or amidated acid group. In a preferred embodiment, the peptide or (.alpha.-)amino acid ester concentration is greater than 50 mM, wherein in a particularly preferred embodiment, the concentration ranges from 100 to 1000 mM with approximately comparable nucleophile and electrophile concentrations. The preferred substrate/enzyme ratios are &gt;10.sup.5 M/M or &gt;10.sup.3 M/M when papain is employed. Phthalyl, maleyl or citraconyl radicals and their derivatives or N-betainyl compounds are envisaged for use radicals (X) in the electrophilic component.

Process for the enzymatic preparation of protected and unprotected di-

The nuclear hydroxylation of phenol can be carried out in an industrially very simple manner and with at least the yields obtained with the known methods as well as with very good selectivities by means of using aqueous hydrogen peroxide with the simultaneous addition of sulfur dioxide or selenium dioxide as catalyst.

Method of producing catechol and hydroquinone

The nuclear hydroxylation of substituted phenols is performed by using aqueous hydrogen peroxide in the presence of sulfur dioxide or selenium dioxide as catalyst in a simple manner with very good space-time yields and good product yields.

Method of preparing substituted dihydroxy-benzenes

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Freigericht, Germany

Karl-Heinz Drauz