Chloroform, condensation with benzaldehyde

Belgian workers needed to prepare the benzylidenethiophthalide 1 to test its potential use as a chain-stopper for a particular polymerisation process. 2-Thiophthalide 2 was therefore condensed with benzaldehyde in THF at 0°C using potassium t-butoxide as base. Work-up consisted simply of addition of water, acidification with HC1 and extraction with chloroform. None of the expected product 1 was obtained instead, the stilbene acid 3 was formed in 52% yield. 

Benzaldehyde, condensation, with N-phenylhydroxylamine, 46,127 with chloroform, 48, 27 reaction with triphenylphosphine and sodium chlorodifluoroacetate, 47, 50... 

Knoevenagel reaction. As surrogate for benzaldehyde in the condensation with active methylene compounds, the benzenesulfonimine is superior. In the presence of EtjN in chloroform the reaction with, inter alia, /8-diketones, )3-keto esters, a-sulfonyl ketones, a-nitro esters, and malononitrile proceeds at room temperature. 

Methyl 2-(3 -Phenyl-2 -propen-r-oyl)phenyl Tellurium3 A stirred mixture of 12 g (46 mmol) of 2-acetylphenyl methyl tellurium, 17.6 m/(18.4 g, 170 mmol) of benzaldehyde, 88 mlof acetic acid, and 35 ml of piperidine is heated under reflux for 6 h. The mixture is then steam-distilled to remove unreacted benzaldehyde. The resultant red oil is separated by extraction with chloroform, the extract is evaporated, and the residue is fractionally distilled under vacuum. The fraction boiling above 200°/0.1 torr is collected and redistilled to give a condensate that should solidify. This solid is recrystallized several times from a mixture of petroleum ether and benzene yield 3.2 g (20%) m.p. 102-104° (from heptane/benzenc). 

The condensation of pyrazole-3-one 260 with substituted benzaldehydes 261a-d was carried out in the solid state, in the molten state and in chloroform solution at 50 °C. Two products, 4-arylidenebispyrazol-3-ones 262 and 4,4 -arylmethylenebis-pyrazoles 263, were obtained, in varying amounts according to the experimental method used (01CHJC398) (Table 1) (Scheme 81). 

Thus, chalcone (26), available via aldol condensation between the appropriate benzaldehyde and acetophenone, was transformed into the 1,3-diarylpropene (27) via a two-step sequence involving ethyl chloroformate and NaBH4, followed by protection of the phenolic hydroxy group as the TBDMS ether. Asymmetric dihydroxylation of olefin (2 7) with AD-mix-a gave an intermediate diol, which was converted into ortho-ester (28) with triethyl orthoformate in the presence of catalytic pyridinium -toluenesulfonate (PPTS), followed by deprotection of the TBDMS ether with TBAF in THE. Treatment of ortho-ester (28) with triethyl orthoformate and PPTS gave an intermediate (27( ,35)- w j -flavan-3-ol formate ester. De-esterification with K2CO3 in THF/methanol and oxidation of the... 

Condensation of a-phenyl-a-acylaminoacetonitriles with aromatic or aliphatic aldehydes by heating at 140° in the presence of zinc chloride, or by treatment in alcohol or chloroform with dry hydrogen chloride, produces Schiff bases of 2-aryl (or alkyl )-4-phenyl-5-aminooxazoles.205 The reaction of benzaldehyde with benzene sulfonamide and potassium cyanide (molar ratio 1.0 0.33 0.2-0.25) at 135° gives a 9-22% yield of 2,4-diphenyl-5-(benzylideneamino)oxazole and has been proposed to proceed through a-benzoylaminophenylacetonitrile.206... 

A mixture of 4.53 g of-aminophenylacetic acid (0.03 mol), 7.9 g pyruvic acid (0.09 mol), and 200 mL water (3.5% deuterium) was boiled under reflux for 3 h. A homogeneous solution was formed within a few minutes after the mixture began to boil. On completion of the reaction, benzaldehyde was removed by distillation through a declining condenser and extracted from the distillate with several small portions of chloroform. The aqueous portion of the distillate and the aqueous reaction mixture were reserved. After drying the chloroform solution over sodium sulfate, the solvent was evaporated and the residual benzaldehyde was converted into the phenylhydrazone by treatment with phenylhydrazine in 50% alcoholic solution. After recrystallization from 60% alcohol, the yield of benzaldehyde phenylhydrazone was 4.3. 4 g, m.p. 155.5-157°C for various preparations. 

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