Benzylidene-, dimethyl

Dimethyl mesoxolate Propanedioic acid, oxo-, dimethyl ester (9) (3298-40-6) Dimethyl benzalmalonate Malonic add, benzylidene-, dimethyl ester (8) Propanedioic add, (phenylmethylene)-, dimethyl ester (9) (6626-84-2) Dimethyl sulfide Methyl suflide (8) Methane, thiobis- (9) (75-18-3)... 

NR2 + R2N = CC12) (4-Chlor-benzyliden)-dimethyl- -tetrafluoroborat E14a/3, 232... 

Acetophenon 4-Methyl- -hydrazon EI4b, 508 (Umhydrazonierung) Ammonium Benzyliden-dimethyl-E2Ib, 1926 [from Ar —CH(NR2)] Benzoesaure -methylamid-methyl-imid E5, 1304 (CO - C = NR) Cyclopenta d -l,2-diazepin 7-Methyl-1,2,3,4-tetrahydro- E9d, 347 [2-(CH = CH — CH3) — cyclopen-ten-l-CH=N-NH-Tos/ NaOR]... 

It is apparent from the foregoing that a more specific method for the determination of xylan would be desirable. To this end, the determination of xylose, after acid hydrolysis of the polysaccharide material, has been attempted. Xylose may be oxidized to xylonic acid which can be precipitated with cadmium bromide as the double salt, but the precipitation is not quantitative. Xylose forms an insoluble, crystalline di-O-benzylidene dimethyl acetal which permits identification in the presence of other sugars, but the necessity for anhydrous reaction conditions precludes the adaptation of this method to ordinary analysis. AVise and Ratliff prepared this derivative of both d- and L-xylose, as well as analogous derivatives from other aromatic aldehydes, and concluded that, with either the di-O-benzylidene or the di-O-(p-isopropylbenzylidene) dimethyl acetal, an excellent, highly specific, qualitative test was available for d- or n-xylose. 

Chromanone, 3-acetamido-2-methyl-reduction, 3, 729 Chromanone, 3-amino-synthesis, 3, 734 Chromanone, 3-arylidene-thermoisomerization, 3, 722 Chromanone, 3-benzylidene-thermolysis, 3, 728 Chromanone, 3-bromo-2-hydroxy-benzofuran from, 3, 729 Chromanone, 6,8-dimethyl-hydroxymethylation, 3, 731 Chromanone, 2,3-epoxy-as synthon, 3, 735... 

Chroman-4-one, 5-acetoxy-3-hydroxy-2,2-dimethyl-synthesis, 3, 857 Chroman-4-one, 3-amino-synthesis, 3, 855 Chroman-4-one, 3-benzylidene-synthesis, 3, 829 Chroman-4-one, 3-bromo-... 

Fig. 8.4. Logarithm of the first-order rate constants for the hydrolysis of substituted benzylidene-l,l-dimethyl-ethylamines as a fiinction of pH. [Reproduced fiom J. Am. Chem. Soc. 85 2843 (1963) by permission of the American Chemical Society.]...

This structure rationalizes (a) the formation of mono- and, under more vigorous conditions, tetra-acetyl derivatives, (b) the methyla-tion to a dimethyl derivative still containing two active hydrogens, (c) the pyrolysis back to monomeric indole, (d) the formation of a benzylidene derivative containing the Ph CH=N— Ar ehromophore, (e) the failure to form a simple nitroso derivative, (f) the Zn/AcOH reduction of the dimethyl trimer to base C18H20N2, shown to be identical with the dihydro derivative of (26). 

N-(4-Chlor-anilinomethyl)- 453 N-(4-Cyan-anilinomethy )- 453 N-(N, 4-Dimethyl-anilinomethyl)- 254 N-Diphcnylmethyl- 255 3 -Hydroxy-N -propyl - 257 N-Methyl-3-benzyl-2-benzyliden- 581 N-Methyl-bis-fbenzylidenJ- 581 N-Methyl-2,3-dibenzyl- 581 N-Phcnyl- 256 N-Pyrrolidinomethyl- 452... 

Oxo-4,4-dimethyl-2-benzyl-4.5-dihydro- 228 5-Oxo-4-methyl-2-benzylidcn-2.5-dihydro- 228 5-Oxo-2-phenyl-4-benzyliden-4,5-dihydro- 228 5-Oxo-2-phenyl-4,5-dihydro- 228 2-Phenyl-4-ch orcarbonyl- 188 2-Phenyl-5-naphthyl-(l)- 591 2-Phenyl-5-naphthyi-(l)-2,3-dihydro- 591... 

These sunscreen ingredients include octyl-dimethyl-PABA (UVB), 2-ethylhexyl-p-meth-oxycinnamate (UVB),octocrylene (UVA/UVB), octyl salicylate (UVB), benzophenones (UVB/ UVA), and methyl anthranilate (UVA). Avoben-zone or Parsol 1789 and mexoryl, a benzylidene camphor, block UVA. Mexoryl is the most efficient of the UVA organic sunscreens [10]. Many sunscreen formulations combine ingredients to maximize photoprotection. 

Fig. 3 Protonation states, isomerism and mesomerism of the HBI chromophore (p-hydroxybenzi-lidene-imidazolinone). The chromophore is shown in its most stable Z ( cw ) conformation, conventionally associated to a 0° value of the dihedral angle t, while the E ( trans ) conformation corresponds to t = 180°. For model compound HBDI (4 -hydroxy-benzylidene-2,3-dimethyl-imidazolinone), Ri = R2 = CH3, for chromophore in GFP, Ri, and R2 stand for the peptidic main chains toward N-terminus and C-terminus, respectively, (a) Possible protonation states of HBI (a) neutral, (b) anionic, (c) enolic, (d) cationic, and (e) zwitterionic. (b) Two resonance structures of the anionic form of HBI...

Useful syntheses of D- and L-lyxose from 1,3-O-benzylidene-D- and L-arabinitol have been achieved through the highly selective oxidation of the primary hydroxyl groups by dimethyl sulfoxide-dicyclohexylcarbodiimide.463 Oxidation of but one of the two (equivalent) hydroxyl groups in 1,3,4,6-tetra-O-benzyl-D-mannitol464 and l,6-di-0-benzyl-2,5-0-methylene-D-mannitol465 was possible with dimethyl sulfoxide-acetic anhydride. 

Reaction of 1 with benzaldehyde and zinc chloride gave a diastereomeric mixture (6) of R- and 5-2,3-O-benzylidene derivatives (4a and 4b). The former (4a) would be identical to the acetal described by Zinner et al. (3) as 2,4-O-benzylidene-D-ribono-1,5-lactone. This structure was further established as 4a, by chemical and physical studies of the product obtained on reaction of 1 with benzaldehyde dimethyl acetal (7). The 2,3-O-benzylidene derivative, obtained by Garegg et al. (8) on reaction of 1 with a,a-dichlorotoluene in pyridine, has the same properties as compound 4a, which would indicate the -configuration for the acetal carbon. 

The square-planar geometry (with slight tetrahedral distortion) of these derivatives can be proved by that of the related Rh(I) complex with 2,2/-bis [o-(diphenylphosphine)benzylidene]amine -6,6/-dimethyl-diphenyl, [Rh(PPNN)]+, Figure 23.26... 

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