24469-79-2Relevant articles and documents
Access to Saturated Thiocyano-Containing Azaheterocycles via Selenide-Catalyzed Regio-A nd Stereoselective Thiocyanoaminocyclization of Alkenes
Wei, Wei,Liao, Lihao,Qin, Tian,Zhao, Xiaodan
, p. 7846 - 7850 (2019/10/10)
An efficient route for the synthesis of saturated thiocyano-containing azaheterocycles by selenide-catalyzed regio-A nd stereoselective thiocyanoaminocyclization of alkenes is disclosed. The desired products were obtained in moderate to high yields under mild conditions. The generality of this method was elucidated by its efficient application in thiocyano oxycyclization of alkenes.
Stereoselective Synthesis of Alcohols containing (Z)- and (E)-Olefins, Dienes, Enynes and Styrenes: Cyclic β-Halogeno Scissions using Samarium Diiodide as the Electron-transfer Agent
Crombie, Leslie,Rainbow, Linda J.
, p. 673 - 688 (2007/10/02)
In contrast to the sodium-mediated ring scission of 2-substituted 3-chloro ethers of the tetrahydrofuran series, samarium diiodide gives olefins of high (E)-stereoselectivity and provides (E)-conjugated and unconjugated dienes, styrenes and enynes in good yield without appreciable over-reduction.Whilst the SmI2 scission of 3-chloro-2-alkyltetrahydropyrans gives (Z)-rich (Z)/(E) olefin mixtures, the 2-(alk-1'-ynyl) members give (Z)-enyne alkohols with high stereoselectivity, providing a valuable complement to the (E)-enyne synthesis employing the tetrahydrofuran series.In electron-transfer scissions using sodium, the stereochemistry of the product alcohols is related to the ground-state conformation of the cis- and trans-pyrans and -furans.The slow SmI2-mediated reactions appear to involve samarium-complexed intermediates having structures independent of the original conformation, or of the cis- or trans-geometry of the furan or pyran, and it is the transition states from these intermediates that determine the stereochemical outcome.Scissions in the tetrahydrofuran series can be accelerated by addition of HMPA or DMPU with only a little deterioration in stereoselectivity, but in the tetrahydropyran series there are drastic changes in product stereochemistry when DMPU is added.Brief comment is made on the synthesis of tetrahydro-furan and pyran precursors.
Ring Scission Of Cyclic β-Halogeno-ethers with Samarium Di-iodide: A Synthesis of (E)- and (Z)-Enynols
Crombie, Leslie,Rainbow, Linda J.
, p. 6517 - 6520 (2007/10/02)
The use of samarium di-iodide in place of sodium metal for the ring scission of cyclic β-halogeno-ethers drastically alters the stereochemistry of the resulting olefinic alcohols: using the method, highly stereoselective syntheses of enynols in (Z)- and (E)-forms are reported.
EVOLUTION THERMIQUE DE N-OXYDES DE DIMETHYLAMINO-5 ALCANOLS-1 SUBSTITUES EN 5. COMPETITION ENTRE REARRANGEMENTS DE COPE ET DE MEISENHEIMER
Barbry, Didier,Hasiak, Bruno,Augait, Jean-Michel,Couturier, Daniel
, p. 956 - 961 (2007/10/02)
The effect of the substituent R in the 5 position was studied in the decomposition of 1,5-aminoalcohol N-oxides: Meisenheimer rearrangements takes place when R is the vinyl group but is not observed with the phenyl substituent; elimination to alkenol only
RETENTION OF CONFIGURATION IN DOUBLE BOND PROTECTION-DEPROTECTION BY BROMINATION-CATHODIC DEBROMINATION
Husstedt, Urda,Schaefer, Hans J.
, p. 623 - 624 (2007/10/02)
The double bond can be mildly protected by bromination with PyHBr3; deprotection is achieved by cathodic reduction at -1.4 V.The overall yields range from 68 to 99 percent, the configuration of the double bond is retained with at least 96 percent.
