Dimethylsulfoxide Diols

The Validity of the J Function. For aqueous sodium hydroxide solutions the validity of the J- function, describing the basicity of a solution by its ability to add hydroxide ions to a carbonyl group to form an anion of the geminal diol, has been proved earlier (19). For all substituted benzaldehydes studied in water-ethanol or water-dimethylsulfoxide (DMSO), the value of log (CArCH(OH)o-/CArCHo) determined from absorbance measurements was found to be a linear function of the J- function with a slope varying between 0.95 and 1.05 in the region of J values where measurements were possible. The Can-... 

Action of tf-Bromosncdnimide In Dimethytsulfoxide. An alternative to die classic methylenation of diols has been offered by the simple procedure using W-bromosuc-cinimide in dimethylsulfoxide and has been applied, for instance, to the acetalation of D-mannitol and D-ribofuranosides [90],... 

Plots of Po/w or vs. plate counts for benzene and 2-ethylanthraquinone eluted with micellar SDS, in the presence of several alkanols and alkane diols, show an initial steep increase in efficiency, after which an approximately constant value is reached (Fig. 3). Among the alcohols, maximal efficiency for benzene and 2-ethylanthraquinone is obtained with the butanols and the pen-tanols, with enhancement factors of 2.5 and 25 (compared to pure SDS), respectively. However, final efficiencies for the latter compound are much lower compared to that for benzene. Dipolar aprotic modifiers (acetonitrile or dimethylsulfoxide) appear to be somewhat more effective in enhancing efficiencies than alcohols with comparable Pq/w- Some recent work has shown the advantage of using acetonitrile as additive in MLC for the analysis of sulfonamides, tetracyclines, and the most polar steroids. 

The usefulness of undercooled water as a reaction medium has also been demonstrated in biochemical studies. Thus, the kinetics of biochemical reaction sequences can be sufficiently slowed down to become time resolved at subzero temperatures in the unfrozen state. Even more importantly, complex reaction pathways (mechanisms) are unaffected by undercooling, whereas the use of conventional cryoprotectants (glycerol, ethane diol, dimethylsulfoxide, etc.) alters the pathways, although not necessarily the nature of the end products. Finally, single cells or even cell clusters can be stored and kept intact for considerable periods in undercooled aqueous media. 

Figure 13 Plot based on Eq. (26) for liquids on a dried film from a latex adhesive. From left to right the liquids are dimethylformamide, dimethylsulfoxide, ethane diol...

Prior to hydroboration of the olefmic double bond, the lactone carbonyl was reduced by diisobutyl aluminium hydride to the corresponding lactol which was treated with HCl in methanol to give the protected lactol (166). Hydroboration afforded the diol (167). The latter was oxidized to the diketone (168). Elaboration of the disphenol units was achieved in a two-step sequence. The diketone (168) was treated with LDA and the resulted di-anion was submitted to the M0O5PH reagent 104) to give in 35% yield the bis-a-hydroxy ketone (169), which was smoothly transformed with sodium methoxide in dimethylsulfoxide into diosphenol (170). Upon methylation (170) gave (171) which was selectively hydrolysed to the racemic neoquassin (172). Oxidation with Fetizon s reagent yielded racemic quassin. Overall yield from the enone (162) was more than 3%. 

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