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21504-23-4

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21504-23-4 Usage

Check Digit Verification of cas no

The CAS Registry Mumber 21504-23-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 2,1,5,0 and 4 respectively; the second part has 2 digits, 2 and 3 respectively.
Calculate Digit Verification of CAS Registry Number 21504-23:
(7*2)+(6*1)+(5*5)+(4*0)+(3*4)+(2*2)+(1*3)=64
64 % 10 = 4
So 21504-23-4 is a valid CAS Registry Number.

21504-23-4Relevant articles and documents

Selective oxidation of vinyl ethers and silyl enol ethers with hydrogen peroxide catalyzed by peroxotungstophosphate

Yamamoto, Hiroyo,Tsuda, Masaya,Sakaguchi, Satoshi,Ishii, Yasutaka

, p. 7174 - 7177 (1997)

The oxidation of vinyl and silyl enol ethers with aqueous hydrogen peroxide was first achieved by the use of peroxotungstophosphate (PCWP) as the catalyst. For example, the oxidation of 1-ethoxy-1-octene with a stoichiometric amount of 35% H2O2 in the presence of PCWP (0.5 mol %) in a mixed solvent of methanol and dichloromethane at room temperature gave 1- ethoxy-1-methoxy-2-hydroxyoctane, a synthetic equivalent of 2- hydroxyoctanal, in 70% yield. The oxidation of acyclic silyl enol ethers such as 1-[(trimethylsilyl)oxy]-1-octene under these conditions gave 1-hydroxy-2- octanone in 725 yield, while the same oxidation in dichloromethane alone resulted in cleavage of the enol double bond to form heptanal in 71% yield. Cyclic silyl enol ethers were converted into the corresponding α-hydroxy ketones in 48-71% yields under similar reaction conditions.

α-Hydroxylation of carbonyls using iodine

Zacuto, Michael J.,Cai, Dongwei

, p. 447 - 450 (2007/10/03)

The α-hydroxylation of ketones and aldehydes to α-hydroxyketals mediated by iodine under basic conditions in MeOH is described. Enolates generated under the reaction conditions are iodinated and the resulting α-iodocarbonyl is transformed into the hydroxyketal. The use of iodine for this chemistry represents an economical and practical alternative to existing methods for this transformation.

ELABORATION OF THE ACYL LIGAND IN (η5-C5H5)Fe(CO)(PPh3)(COCH2OCH3)

Guo, Zhong-Wu,Zamojski, A.

, p. 119 - 129 (2007/10/02)

Deprotonation of the complex (η5C5H5)Fe(CO)(PPh3)(COCH2OCH3) leads to anion 7 which can be alkylated stereoselectively to products of RFeRα/SFeSα configuration.Reaction of 7 with acetaldehyde or benzaldehyde are not stereoselective and yield four stereoisomeric products 16-19 or 20-23, respectively.Exchange of the lithium cation for diethylaluminium or divalent tin cations improves the stereoselectivity in reaction of 7 with carbonyl compounds.Reaction of 7 with acetone leads to product 24 of the RFeSα/SFeRα configuration.Decomplexation of 20with NBS and methanol is connected with decarbonylation and leads to mandelaldehyde dimethyl acetal.With other alcohols mixtures of diastereoisomeric mixed acetals are formed.Similar results are achieved with other mild oxidizing reagents as cerium ammonium nitrate or selenium dioxide.Oxidation of 20 with m-chloroperoxybenzoic acid leads mainly to one of the diastereoisomeric acetals although in a low yield.Decomplexation of 15 with NBS and ethanol leads to mixed acetal 29.

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