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166757-18-2

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166757-18-2 Usage

Check Digit Verification of cas no

The CAS Registry Mumber 166757-18-2 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,6,6,7,5 and 7 respectively; the second part has 2 digits, 1 and 8 respectively.
Calculate Digit Verification of CAS Registry Number 166757-18:
(8*1)+(7*6)+(6*6)+(5*7)+(4*5)+(3*7)+(2*1)+(1*8)=172
172 % 10 = 2
So 166757-18-2 is a valid CAS Registry Number.

166757-18-2Relevant articles and documents

Stereoselective Synthesis of Oxabicyclo[2.2.1]heptenes via a Tandem Dirhodium(II)-Catalyzed Triazole Denitrogenation and [3 + 2] Cycloaddition

Yuan, Hao,Gong, Jianxian,Yang, Zhen

, p. 5500 - 5503 (2016)

A novel synthetic strategy for the diastereoselective synthesis of structurally diverse oxabicyclo[2.2.1]heptenes has been developed, featuring a tandem reaction combining a Rh-catalyzed triazole denitrogenation and a novel type of [3 + 2] cycloaddition reaction. This tandem reaction was thought to proceed via a five-membered oxonium ylide intermediate, which was formed by the intramolecular nucleophilic attack of the carbonyl group on the α-imino metallocarbene followed by an inter- or intramolecular [3 + 2] dipolar cycloaddition with a range of alkynes and alkenes.

Rapid Access to Oxabicyclo[2.2.2]octane Skeleton through Cu(I)-Catalyzed Generation and Trapping of Vinyl-o-quinodimethanes (Vinyl-o-QDMs)?

Luo, Hejiang,He, Chuan,Jiang, Huanfeng,Zhu, Shifa

, p. 1052 - 1056 (2020/07/04)

A Cu(I)-catalyzed three-component reaction of terminal enynals/enynones, diazo compounds, and alkenes has been developed. With this method, a series of oxabicyclo[2.2.2]octanes were effectively synthesized in high yields under mild reaction conditions. This transformation is proposed to proceed through trapping of the cyclic vinyl-o-quinodimethanes (vinyl-o-QDMs) species, which were generated from terminal enynals/enynones and diazo compounds by alkenes. The obvious advantages of wide substrate scopes, mild reaction conditions, and high seteroselectivity and atom efficiency make this reaction highly appealing for construction of highly rigid [2.2.2]octane skeleton.

An Unusual Example of a 6-Endo-Dig Addition to an Unactivated Carbon-Carbon Triple Bond

Padwa, Albert,Krumpe, Keith E.,Weingarten, M. David

, p. 5595 - 5603 (2007/10/03)

Methyl 2-ethynyl>benzoate was prepared as an intermediate for subsequent conversion to an α-diazo ketone.Under the basic conditions used to hydrolyze the methyl ester, the neighboring hydroxyl functionality underwent reaction with the unactivated acetylenic group, producing a benzopyranyl-substituted α-diazoacetophenone.Treatment of this diazocarbonyl compound with a catalytic quantity of rhodium(II) mandelate afforded a novel dibenzocyclononenone derivative.The reaction proceeds via an initially formed oxonium ylide which rearranges further by means of a 1,2-alkyl shift.A prime factor in determining the direction of internal cyclization to the triple bond is the presence of the carbomethoxy group in the ortho position of the β-phenyl ring.Thus, in contrast with related systems which exhibit a clear preference for 5-exo-dig cyclization at the acetylenic center, the 6-endo-dig addition is the preferred pathway for the o-formyl- and o-carbomethoxy-substituted alkynyl alcohols.Careful monitoring of the reaction actually showed that the reaction proceeds by initial formation of the 5-exo-dig product followed by a novel rearrangement to the 6-endo product.

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