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157020-39-8

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157020-39-8 Usage

Check Digit Verification of cas no

The CAS Registry Mumber 157020-39-8 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,5,7,0,2 and 0 respectively; the second part has 2 digits, 3 and 9 respectively.
Calculate Digit Verification of CAS Registry Number 157020-39:
(8*1)+(7*5)+(6*7)+(5*0)+(4*2)+(3*0)+(2*3)+(1*9)=108
108 % 10 = 8
So 157020-39-8 is a valid CAS Registry Number.

157020-39-8Relevant articles and documents

Novel Enantioselective Syntheses of (+)-Biotin

Deroose, Frederik D.,De Clercq, Pierre J.

, p. 321 - 330 (2007/10/02)

Two conceptually attractive enantioselective syntheses of (+)-biotin from L-cysteine are reported based upon an intramolecular 1,3-dipolar cycloaddition of a carbamoyl azide.The first approach (12 steps) involves the following as key-steps: (i) the macrothiolactonization of acid 10b to Z-olefin 14, (ii) the thermolysis of the ene carbamoyl azide 15 in water with direct formation of a mixture of the benzylated derivatives of (+)-biotin 16a and 17a.The second approach (14 steps) involves the following: (i) elimination of bromide 29 to the endocyclic thioenol ether 30, (ii) thermolysis of the ene carbamoyl azide 30 to the exocyclic thioenol ethers 31a and 31b.Both the synthesis of 29 and the final transformation of 31a and 31b into (+)-biotin are based upon literature precedents.

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