A variation of Mattox rearrangement mechanism under alkaline condition

Nucleophilic Trapping of Alkoxy-Stabilized Oxyallyl Systems Generated from Inosose 2-O-Mesylates

“…18 A base-promoted variant of this rearrangement on betamethasone dipropionate has been reported by Li et al who proposed hydrolysis and rearrangement of an intermediate enol. 19 The characterization of ketal 8 was performed using 1D and 2D 1 H and 13 C NMR spectroscopy. A methylene group, not present in the starting material, was assigned on the basis of two upfield resonances at δ = 2.87 and 2.73 ppm in the 1 H NMR spectrum.…”

Development and validation of a stability-indicating HPLC method for simultaneous determination of salicylic acid, betamethasone dipropionate and their related compounds in Diprosalic Lotion®

“…The degradation pathway of BD and SA were also well characterized [4][5][6][7][8]. Expired Diprosalic Lotion ® samples and an expired batch (age of 32 months) spiked with all related compounds of BD and SA (Table 1) should provide a true reflection of degradation products under the worst case scenario.…”

“…The synthetic process for the production of BD introduces precursor impurities such as betamethasone, betamethasone 17-and 21-monopropionates [4], which can also form when BD is exposed to acidic or basic conditions. In formulated drug products, BD can form other degradants such as betamethasone enolaldehydes [4][5][6].…”

“…In formulated drug products, BD can form other degradants such as betamethasone enolaldehydes [4][5][6]. Synthetic SA may contain impurities such as 4-hydroxybenzoic acid, 4-hydroxyisophthalic acid and phenol.…”

Advances in the analysis of steroid hormone drugs in pharmaceuticals and environmental samples (2004–2010)

“…In the course of these studies online HPLC/UV and HPLC/MS(MS) with off-line MS and NMR after semi-preparative HPLC separation were used [38][39][40][41][42][43]. The main results were the identification of the epimeric 16␣-methyl derivative (dexamethasone-17-valerate) as a process impurity in betamethasone-17-valerate [38], the identification of 4 diastereomeric 17-deoxy-20-hydroxy-21-oic acid-type solidphase degradation products of betamethasone sodium phosphate [39] (see Fig.…”