Carbinols, aryl

Methyl groups in pyridopyrazines (64IMC240) and pyridopyrazinones (71TH21500) are oxidized to carboxylic acids with potassium permanganate. Aryl carbinol substituents are also very readily oxidized to benzoyl derivatives in alkaline conditions (76CPB238). Bromina-tion of 2,3-dimethylpyrido[3,4-f ]pyridazine gives the 2,3-bisbromomethyl derivative, whilst... 

Scheme 13 Spivey s axially-chiral analog of 4-DMAP in the KR of an alkyl aryl carbinol. [117-127]...

Ha reflects the ability of the solvent system to donate protons, but it can be applied only to acidic solutions of high dielectric constant, mostly mixtures of water with acids such as nitric, sulfuric, perchloric, etc. It is apparent that the H0 treatment is valid only when /i//hi s independent of the nature of the base (the indicator). Since this is so only when the bases are structurally similar, the treatment is limited. Even when similar bases are compared, many deviations are found.85 Other acidity scales86 have been set up, among them H for bases with a charge of - 1, //R for aryl carbinols,87 Hc for bases that protonate on carbon,88 and HA for unsubstituted amides.89 It is now clear that there is no single acidity scale that can be applied to a series of solvent mixtures, irrespective of the bases employed.9"... 

Adler E, Marton J (1961) Carbonyl groups in lignin II Catalytic hydrogenation of model compounds containing aryl carbinol, aryl carbinol ether, ethylene and carbonyl groups Acta Chem Scand 15 357-369... 

The methyl ethers of many aryl carbinols cleave in Et20 with liq Na-K alloy or with potassium powder (reaction of the latter is facilitated with the aid of small-edged pieces of quartz glass to cut through incrustations on the potassium on shaking), e.g. ... 

Cp2TiCl2 reacts with MgCIPr1 in the presence of cycloheptatriene to give 73-cycloheptadienyltitanium isomers (Scheme 491), which undergo in situ addition to aldehydes to produce a mixture of 1,3- and 1,4-cycloheptadienyl alkyl (aryl) carbinols. The reaction opens a simple way to functionalized 1,4-cycloheptadienes, some of which are closely related to biologically active compounds.1159... 

Figure 3. Chiral recognition model showing the relative arrangement for three simultaneous bonding interactions between (K)-CSP 1 and the most retained enantiomer of an alkyl aryl carbinol.

All other cross-couplings involving terminal alkynes and halo amides have involved ring closure on nitrogen. Thus, o-halobenzamides react with simple terminal alkynes in the presence of a Pd/Cu catalyst to afford either (Z)-3-aryl(alkyl)idene isoindolin-l-ones or the corresponding 2-(l-alkynyl)benza-mides, which are readily cyclized by NaOEt/EtOH or Pd(OAc)2 catalyst to give isoindolin-l-ones (Eq. 11) [35,36]. When acetylenic aryl carbinols are employed as the alkynes, 3-(acylmethyl)isoindolin-l-ones are obtained instead (Eq.l2) [37]. 

Asymmetric reductive alkylation has also been reported in reactions between benzaldehyde and chiral alkyl(trialkoxy)titanium reagents aryl carbinols are obtained with up to 88% e.e., best results coming from the menthol or binaphthol derivatives, (19) and (20), respectively. 

Particularly good at separating the enantiomers of aryl carbinols... 

Products from the DKR of alkyl aryl carbinols with 9b and ISCBCL. 

Cadiemo et al. (2009) also reported a simple and ecofriendly Meyer-Schuster rearrangement of propargylie aryl carbinols into a, 3-unsaturated carbonyl compounds under microwave irradiation. They catalyzed the rearrangement by InCl3 in aqueous medium. 

We may now inquire into the reason for the difference between the behavior of carbonium ions and ammonium or oxonium ions assuming, as is reasonable (87), that the difference in activity coefficient ratios does not reside in the free bases. An attractive explanation may be advanced at once that the carbonium ions derived from aryl carbinols or olefins involve a much greater degree of charge delocalization than that in the onium ions and this should have a profound effect on how tightly the ion is solvated. At least three facts eliminate the de-localization theory. Firstly, the small NO+ ion, in which delocalization is restricted, has activity coefficient behavior like a polyaryl carbonium ion (82). Secondly, aryl and diaryl ketones behave for the most part as proper Hammett bases (324,328) although considerable delocalization occurs in their ions. Thirdly, the same acidity function seems to apply equally well to pyrrole bases whether or not they have much charge delocalization in their ions (357). 

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