1971
DOI: 10.1021/jo00806a001
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Steroid conjugates. VI. Improved Koenigs--Knorr synthesis of aryl glucuronides using cadmium carbonate, a new and effective catalyst

Abstract: The 3-0-D-glueuronide triacetate methyl esters of estrone, 170-estradiol, estriol, equilin, and equilenin and the 3-0-D-glucoside tetraacetate of estrone were obtained in yields of 46-71% by direct crystallization from a Koenigs-Knorr reaction using a glycosyl halide and the novel catalyst, cadmium carbonate. This represents an approximately tenfold improvement in yield over previously reported methods. Evidence was obtained which suggests that the actual catalyst in these reactions is the resulting cadmium ha… Show more

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Cited by 119 publications
(13 citation statements)
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“…New methodologies are still being developed with more advanced variations in the mechanistic pathways. Later Zémplén and Gerecs, and subsequently Helferich and Wedermeyer, illustrated the principle of the metal(II) salt‐induced removal of leaving groups . With the general standardization of glycosyl protocols, efforts were made to control the stereochemical outcome of glycosylations.…”
Section: General Aspectsmentioning
confidence: 99%
“…New methodologies are still being developed with more advanced variations in the mechanistic pathways. Later Zémplén and Gerecs, and subsequently Helferich and Wedermeyer, illustrated the principle of the metal(II) salt‐induced removal of leaving groups . With the general standardization of glycosyl protocols, efforts were made to control the stereochemical outcome of glycosylations.…”
Section: General Aspectsmentioning
confidence: 99%
“…This reaction is particularly sluggish with less reactive perbenzoylated bromides. To advance the classical Koenigs–Knorr glycosylation, many activators including salts of mercury, [58] cadmium, [911] tin, [12,13] zinc, [14,15] indium, [16,17] silver [1826] have emerged. [27] Nevertheless, these modifications failed to adequately enhance the reaction that continued to suffer from fair yields, poor reactivity of donors, substrate scope, and the requirement to use excess of toxic or expensive reagents.…”
mentioning
confidence: 99%
“…Using compound 8 as starting material in reaction with lamotrigine ( 9) , only a low 8% of the N -glucuronide 11 was obtained by this method. Instead, reactions with CdCO 3 , previously reported to be an efficient base in N -glycosylations, were tested on both 5a and 8 [ 33 , 34 , 35 ]. In both cases a rapid conversion towards the product was evident when the coupling was performed in refluxing nitromethane ( Scheme 4 ).…”
Section: Resultsmentioning
confidence: 99%
“…The reason for the conversion improvement upon using CdCO 3 is not firmly established. However, it has been reasoned that the in situ formation of a Cd 2+ halide is responsible for a heterogeneous catalysis involving these speices [ 33 ].…”
Section: Resultsmentioning
confidence: 99%