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81757-22-4

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81757-22-4 Usage

Check Digit Verification of cas no

The CAS Registry Mumber 81757-22-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,1,7,5 and 7 respectively; the second part has 2 digits, 2 and 2 respectively.
Calculate Digit Verification of CAS Registry Number 81757-22:
(7*8)+(6*1)+(5*7)+(4*5)+(3*7)+(2*2)+(1*2)=144
144 % 10 = 4
So 81757-22-4 is a valid CAS Registry Number.

81757-22-4Relevant articles and documents

Synthesis of (+)-(5S,6S)-Azafrin Methyl Ester; Absolute Configuration of Aeginetic Acid and of Further Vicinal Apocarotene-diols

Eschenmoser, Walter,Uebelhart, Peter,Eugster, Conrad Hans

, p. 353 - 364 (2007/10/02)

We describe the synthesis of a series of optically active vicinal apo-β-carotene-diols.Thus, starting from (+)-(5S,6S)-5,6-dihydroxy-5,6-dihydro-β-ionone (2) we have prepared the (Z/E)-isomeric(+)-C15-esters 7 and 8, the (+)-retinoic derivatives 14, 15, 18, 19 and (+)-methyl azafrinate (22), the enantiomer of the naturally occuring compounds (s.Scheme 1).Our synthesis also establishes the absolute configuration of aeginetic acid (24), aeginetoside (25) and aeginetin (26), compounds isolated from the root parasite Aeginetia indica by Indian and Japanes workers (s.Scheme 2).The presented synthesis of optically active methyl azafrinate confirms our previous assignment of the absolute configuration of azafrin (1a), which was based on degradative evidence.

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