Bogert reaction

When the alcohol containing portion is acyclic, the reaction is known as the Bogert Reaction-. O... 

The Bogert synthesis of 2,4-diarylthiophenes consisting of the reaction of sulfur with the anils of arylalkyl ketones, has been shown to lead to a mixture of 2,4- and 2,5-disubstituted thiophenes. ... 

It was found inadvisable to use more than four molecules of form-amide [ (47) when R = H] per molecule of anthranilic acid and the condensation produces best results when the mixture is heated at 120 -130°C for 2 hr followed by further heating at 170°-180 C for 2 hr. Other variants of this reaction involve the use of ammonium o-acylaminobenzoates, anthranilic acid in the presence of nitriles and acetic anhydride, o-acetamidonitrile with acetic anhydride or hydrogen peroxide, anthranilic esters and aliphatic or aromatic amides or amidines, isatoic anhydride with amides or amidines, and anthranilic esters with aryl iminochlorides in acetoned The mechanism proposed by Bogert and Gotthelf has had experimental supporR and is represented in Scheme 12. 

Examples of this reaction have long been known, and several have been discussed above (pp. 99-102). Applications of the method to aldehydes of the aromatic series have been reported more recently. Nenitzescu and Gav t observed that equimolal mixtures of benzalde-hyde or anisaldehyde with formaldehyde led to thfe formation of both possible acids and alcohols, and that if formaldehyde was present in large excess the aromatic, alcohol, and little of the corresponding acid, was formed. The procedure may therefore be looked upon as a method for reducing aromatic aldehydes. Davidson and Bogert have worked out experimental conditions for carrying out the reduction of aldehydes by this means to give 85-90% yields of the alcohols. 

Reactions of this kind were introduced when Bogert and Hand heated 2-aminobenzoic acid with acetic anhydride in the presence of ammonium carbonate and obtained a low yield of 2-methylquinazolin-4-one (see l).300 In stages, this reaction was developed to give annelated pyrimidin-4-ones bearing alkyl or aryl groups in both the 2- and 3-positions (see Scheme 2). 

An alkene unit can also be used to generate a cation and cyclize to form a polycyclic aromatic compound. When 229 reacted with acetaldehyde, 230 was produced and this was cyclized by treatment with sulfuric acid to give hydronapthalene (231). This modification does not incorporate the additional ring of the cyclic ketones used in the Bogert-Cook reaction it is sometimes called the Bogert synthesis. 

It is a solid substance having a melting point 126-127°C and a molecular formula CigHjg. Based on the results of oxidation reactions. X-rays crystal analysis coupled with absorption spectrum measurements it was revealed that the hydrocarbon in question could be 3 -methyl-l 2-cyclopentanophenanthrene. The next essential step was to establish the structure of this compound by synthesis, e.g., that of Harper a/ (1934) who used the Bogert-Cook method commencing from ... 

In 1880, Hofmann reported the first preparation of benzothiazole from 2-aminobenzenethiol and formamide. Hofmann stated that benzothiazoles were formed by the interaction of 2-aminobenzenethiol and aldehydes. Bogert et al. later confirmed the same as part of their own studies on the derivatives of thiazoles,during which they synthesized 6-chloro-2-phenyl-benzothiazole. Hofmann had noted only formation of 2- anilinobenzothiazole from the reaction of 2-aminothiophenol and phenyl isothiocyanate. 

This reaction is related to the Bogert-Herrera Reaction and Volhard-Erdmann Cyclization ... 

In 1905, Bogert and Chambers described the synthesis of 32 via the acetanthranil intermediate 31, which was formed by heating 2-amino-6-nitrobenzoic acid (30) with acetic anhydride." It was reported that the yield for this reaction was nearly quantitative. This modification was compared to other variations known at that time, including heating the ammonium salt of anthranilic acid with formamide and heating the ammonium salt of N-acetylanthranilic acid, and proved to be superior. A 4-quinazolone without a substituent at the 3-position (35) has also been prepared by this method. ... 

Bodroux-Chichibabin Aldehyde Synthesis Bogert-Cook Synthesis Bohn-Schmidt Reaction... 

Bogert-Cook Reaction Timothy T. Curran 4.3.1 Description... 

The mechanism of the Bogert-Cook reaction has been shown to be substrate dependent and different transition states have been used to explain different products observed. However, in general, starting with an alcoholic substrate 19a,b, protonation of the hydroxyl group and loss of water to generate the carbocation 20a,b (which could either result in alkene formation, cyclization. 

Initially, Bogert proposed that this reaction always went through an alkene intermediate due to the observation that when the reaction was stopped (quenched before completion) the presence of an olefinic substrate was supported by 30-40 mol % uptake of Br2, while others have thought alkene or carbocation formation unnecessary. An alternative mechanism for some substrates has been proposed in light of experimental results. The key experiments for this alternative mechanistic view was done by Barnes and Olin, wherein they described the reaction of trans-racemic and trans-optically-enriched alcohol 24 with 90% H2SO4 to provide mainly the cis-isolated product 25 which when optically enriched 24 was used, the product 25 rotated plane-polarized light. These results suggested that an alternative mechanism without free cation formation and/or intermediate alkene formation was possible. ... 

---