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502495-29-6

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502495-29-6 Usage

Check Digit Verification of cas no

The CAS Registry Mumber 502495-29-6 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 5,0,2,4,9 and 5 respectively; the second part has 2 digits, 2 and 9 respectively.
Calculate Digit Verification of CAS Registry Number 502495-29:
(8*5)+(7*0)+(6*2)+(5*4)+(4*9)+(3*5)+(2*2)+(1*9)=136
136 % 10 = 6
So 502495-29-6 is a valid CAS Registry Number.

502495-29-6Relevant articles and documents

New Convergent Synthesis of 1α,25-Dihydroxyvitamin D3 and Its Analogues by Suzuki-Miyaura Coupling between A-Ring and C,D-Ring Parts

Hanazawa, Takeshi,Koyama, Akiko,Nakata, Kunio,Okamoto, Sentaro,Sato, Fumie

, p. 9767 - 9772 (2003)

A new convergent method for the synthesis of 1α,25 -dihydroxyvitamin D3 and its analogues has been developed that involves efficient preparation of the A-ring part 1a, (Z)-(3S,5R)-1-bromom-ethylene-3,5-bis(tert-butyldimethylsilyloxy) -2-methylenecyclohexane, starting from epichlorohydrin (4) and its Suzuki-Miyaura coupling reaction with the C,D-ring part 12. Thus, (R)-4 was converted to (3S,5R)-5-(tert-butyldimethylsilyloxy)-8-(trimethylsilyl)-oct-l-en-7-yn-3-ol (3a) through a ten-step reaction sequence in 49% overall yield. Compound 3a thus obtained was treated with a Ti(O-i-Pr)4/2 i-PrMgCl reagent and then with NBS to afford (Z)-(1S,2S,5R)-2-bromomethyl-3-[bromo-(trimethylsilyl)methylene] -5-(tert-butyldimethylsilyloxy)cyclohexanol (10a) in 51% yield, from which la was obtained in 87% yield by sequential treatment with TBSCl/imidazole, DBU, and Cs2CO3. The resulting A-ring intermediate 1a was reacted with alkenylboronate 12 in the presence of a PdCl2(dppf) catalyst to furnish 1α,25 -dihydroxyvitamin D3 in 82% yield after protodesilylation. Similarly, all of the other three possible stereoisomers of A-ring parts 1b, 1c, and 1d were prepared, from which 1-epi-, 3-epi-, and 1,3-di-epi-1α,25-dihydroxyvitamin D3 were synthesized by coupling with 12 in excellent yield, respectively. Starting from 1a and 1c, des-C,D-1α,25-dihydroxyvitamin D3 analogues, retiferol 13 and its 3-epi derivative, were also prepared, respectively.

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