Chlorobenzaldehyde derivatives

GC/MS analysis of PFBOA-derivatives can be performed by either El or chemical ionization. Chemical ionization is performed in positive ion mode (PICI) using methane as a reagent gas. In this analysis, abundant protonated [M + H]+ ion of acetaldehyde-derivatives at m/z 240, diacetyl-mono derivatives at m/z 282 and of internal standard o-chlorobenzaldehyde derivatives at m/z 336, form, and an abundant formation of [M + H—18]+ ion of acetoin-derivatives at m/z 282, is observed. Mass spectra of acetaldehyde, diacetyl monooxime, acetoin and o-chlorobenzaldehyde PFB-derivatives recorded in the PICI analysis of a standard solution are reported in Figure 1.19. 

The sonoelectrooxidation of 4-chlorophenylacetate was also examined.58 This substrate is known to favor markedly the 2-e mechanism and leads to an appreciable yield of 4-chlorobenzaldehyde-derived products (Table 3). 

Reduction of carbonyl groups Terpene and aromatic aldehydes (lOOppm) were reduced by microalgae. In a series of chlorinated benzaldehyde, m - or p-chlorobenzaldehyde reacted faster than the o-derivative. Due to toxicity, the substrate concentrations are difficult to increase. Asymmetric reductions of ketones by microalgae were reported. Thus, aliphatic " and aromatic " ketones were reduced. 

In the first step, (R)-2-chlorobenzaldehyde cyanohydrin is prepared by the almond meal-catalyzed addition of HCN to 2-chlorobenzaldehyde. The cyanohydrin is then transformed into the corresponding 2-hydroxy ester by Pinner reaction. Subsequently, the hydroxy group is activated by sulfonylafion and reacted with tetrahydrothieno[3.2-c]pyridine to give, under complete inversion of configuration, the (5 ) — a-amino acid derivative CLOPIDOGREL. ... 

The poor performance of the distyryldiphenyl derivative 11.15 at higher washing temperatures is a serious drawback in some countries. In an attempt to overcome this disadvantage, product 11.15 has been marketed in admixture with an analogous FBA (11.64) derived from 4-chlorobenzaldehyde-3-sulphonic acid (see Scheme 11.5). This much less soluble variant is highly effective at high washing temperatures. 

Multicomponent reaction of 2-aminomethylpiperidine benzyl isocyanate and 4-chlorobenzaldehyde in the presence of InCl3 as catalyst provided 4-benzylimino-3-(4-chlorophenyl)pyrido[l,2-+]pyrazinium chloride <2005OL2329>. First, a 3,4-dihydro-477 derivative was formed, which was oxidized under the reaction conditions. Reaction of... 

After these results had established the feasibility of generating and utilizing a carbohydrate phosphorane, the two systems that had been reported earlier were examined in order to determine if similar conditions would allow them to undergo the Wittig reaction. The ylide derived from phosphonium salt I condensed with both benz-aldehyde and U-chlorobenzaldehyde to produce good yields of olefinic products Villa and Vlllb. The ylide derived from phosphonium salt II also was successfully condensed with benzaldehyde, but the yield of IX was only 30 , presumably because of its extremely poor solubility even in an HMPA-THF solvent mixture. Both of these systems supported the tenet that it was possible to use unstabilized carbohydrate phosphoranes if the conditions are proper and if the g-oxygen is attached to the carbohydrate through another set of bonds. 

Figure 6.9 Bifunctional 3-amino quinuclidine derivatives 30 and 31 and DABCO probed in the MBH reaction between methyl acrylate and o-chlorobenzaldehyde.

Rhodium induced ylide formation (52) between the vinyl diazo derivative 139 and -chlorobenzaldehyde led to the production of 141. The major products from this ylide were the stereoisomeric epoxides 142 and 143 from collapse of the ylide. The epoxides were accompanied by a significant quantity of dihydrofuran 144 from the cyclization of the ylide through the vinyl substituent. 

Schiff bases (112) derived from 4-chlorobenzaldehyde and 1-substituted-5-amino-3-methylthio-l,2,4-triazoles (111) underwent cyclization with phe-noxyacetyl chloride or dichloroacetic acid in the presence of phosphoryl chloride and dimethylformamide to give the 7-(4-chlorophenyl)-fram-6,7-dihydro-3-methylthio-6-phenoxy-l-substituted-l,2,4-triazolo[4,3-a]pyrimidin-5-one 113 and l-substituted-6-chloro-7-(4-chlorophenyl)-3-methylthio 1,2,4-triazolo[4,3-a]pyrimidin-5-one 114, respectively (88JHC173) (Scheme 47). 

An interesting variation in reactivity has also been shown20 in the carbocyclic series on reaction of Schiff s base derived from aniline and p-chlorobenzaldehyde with a number of isomeric dichlorotoluenes. 2,4-Dichlorotoluene yields only the expected stilbene 2,5-dichloro-toluene, according to reaction conditions and molar ratios, gives either the stilbene or 1,2,3-triarylpropane, whereas 2,6-dichlorotoluene yields only the addition product 24. 

In 1992, O Donnell succeeded in obtaining optically active a-methyl-a-amino acid derivatives 49 in a catalytic manner through the phase-transfer alkylation of p-chlorobenzaldehyde imine of alanine tert-butyl ester 48 with cinchonine-derived la as catalyst (see Scheme 4.16) [46]. Although the enantioselectivities are moderate, this study is the first example of preparing optically active a,a-dialkyl-a-amino acids by chiral phase-transfer catalysis. 

A few years later, Sheets suggested that co-oxidation of the biimidazole derived from 2-chloro-3, 4 -dimethoxybenzoin and o-chlorobenzaldehyde and 2-(o-chlorophenyl)-4,5-diphenylimidazole would give a still less expensive photo-oxidant (Scheme 4.13) with less visible sensitivity, thus making for better photofixing. 

Recently, the photocycloaddition of L-ascorbic acid derivatives 73 with 4-chlorobenzaldehyde and benzylmethyl ketone was described which led to preferential attack on the less hindered a-face of the enone to give the oxetanes 74 and 75 (Sch. 20), respectively, with approximately 2 1 regioselectivity (33% de both) [65]. When the substrate is changed to... 

Analogous to epoxides, aziridines can be prepared by the methylenation of imines. In this case, ethyl diazoacetate is the most common source of carbenes. For example, the imine derived from p-chlorobenzaldehyde 148 is converted to the c/j-aziridinyl ester 149 upon treatment with ethyl diazoacetate in the presence of lithium perchlorate <03TL5275>. These conditions have also been applied to a reaction medium of the ionic liquid l-n-butyl-3-methylimidazolium hexafluorophosphate (bmimPFe) with excellent results <03TL2409>. An interesting enantioselective twist to this protocol has been reported, in which a diazoacetate derived from (TJ)-pantolactone 150 is used. This system was applied to the aziridination of trifluoromethyl-substituted aldimines, which were prepared in situ from the corresponding aminals under the catalysis of boron trifluoride etherate <03TL4011>. 

The reactions of CpTiCl3 with 4-amino-3-mercapto-6-methyl-5-oxo-l,2,4-triazine and its Schiff bases (derived from benzaldehyde, 2-chlorobenzaldehyde, anisaldehyde, salicylaldehyde, 2-hydroxynaphthaldehyde, and 2-hydroxyace-tophenone) have been studied in THF and CH2G12 in the absence and presence of amine in different molar ratios.997... 

Figure 1.19 Mass spectra of acetaldehyde PFB-oxime (a), diacetyl mono PFB-oxime (b), acetoin PFB-oxime derivative (c), and o-chlorobenzaldehyde PFB-oxime (d) recorded in the GC/MS analysis of standard solution performed in positive ion chemical ionization mode using methane as reagent gas (reagent gas flow 1 mL/min ion source temperature 200 °C). Flamini et al., (2005) Monitoring of the principal carbonyl compounds involved in malolactic fermentation of wine by synthesis of 0-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine derivatives and solid-phase-microextraction positive-ion-chemical-ionization mass spectrometry analysis, Journal of Mass Spectrometry, 40, p. 1561. Copyright John Wiley Sons, Ltd. Reproduced with permission...

The first example of preparing ophcaHy achve a a-dialkyl-a-anhno acids by chiral PTC was reported by O Donnell in 1992 [36], giving moderate enanhoselec-hvities for the alkylation of p-chlorobenzaldehyde imine of alarhne tert-butyl ester 39a with cinchonine-derived Ic as catalyst (entry 1, Table 11.4). Subsequenhy,... 

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