Regioselectivity Influences in Platinum-Catalyzed Intramolecular Alkyne O-H and N-H Additions
The steric and electronic drivers of regioselectivity in platinum-catalyzed intramolecular hydroalkoxylation are elucidated. A branch point is found that divides the process between 5-exo and 6-endo selective processes, and enol ethers can be accessed in good yields for both oxygen heterocycles. The main influence arises from an electronic effect, where the alkyne substituent induces a polarization of the alkyne that leads to preferential heteroatom attack at the more electron-deficient carbon. The electronic effects are studied in other contexts, including hydroacyloxylation and hydroamination, and similar trends in directionality are predominant although not uniformly observed.
Costello, Jeff P.,Ferreira, Eric M.
supporting information
p. 9934 - 9939
(2019/12/24)
Progressive direct iodination of sterically hindered alkyl substituted benzenes
Benzene derivatives bearing at least one bulky alkyl group (i-Pr or t-Bu) were selectively and effectively iodinated using elemental iodine activated, by 1-(chloromethyl)-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) (Selectfluor, F-TED
Stavber, Stojan,Kralj, Petra,Zupan, Marko
p. 1513 - 1518
(2007/10/03)
Aromatic iodination with the I2-HgX2 combination
The reaction of differnt aromatic compounds 1a-1t with iodine and a mercury(II)-salt 2 [mercury(II) chloride, nitrate or triflate] (1:1:1 molar ratio) in dichloromethane at room temperature leads to the corresponding iodoarene 3, the obtained regiochemistry being the expected. Concerning the mercury(II) salt, the observed reactivity decreased in the series triflate > nitrate > chloride according to their ionic character. An activation of the iodine molecule by the mercury(II) salt followed by a S(E) reaction with the aromatic compounds is postulated as the possible mechanism.
Bachki, Abderrazak,Foubelo, Francisco,Yus, Miguel
p. 5139 - 5146
(2007/10/02)
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