Treibs Reaction

A modified Treibs reaction has been used to convert dehydroepiandrosterone into 3/3-acetoxy-6/3-hydroxyandrost-5-en-17-one reaction is by means of mercury(n)... 

Allylic substitution of steroidal olefins by a modified Treibs reaction has been described." With mercury(ii) trifluoroacetate, allylic substitution of steroidal olefins (3/3-hydroxyandrost-5-en-17-one acetate, cholesterol derivatives) proceeded under milder conditions (even at 0°C) than with mercury(ii) acetate the 6jS-hydroxy-A -compounds were obtained. Similarly, paravallarine derivatives (46 R = H, Me, COMe, or COCF3) gave 6/8-hydroxy-compounds (47) (yields 18—46%). In this case it was possible to isolate, in neutral medium, the isomeric 4/8-hydroxy-A -compounds (48). 

Mercuric trifluoroacetate 2-Ethylenealcohols from ethylene derivs. Modified Treibs reaction... 

All acid-catalyzed electrophilic substitution reactions are held by Treibs to occur by way of the distinct reactive species (23), thus the very greatly accelerated interaction of pyrrole and formaldehyde in acid solution involves attack of neutral formaldehyde on (23). Another example is the interaction of 2,3,4,6-tetramethylpyrrole with p-dimethylaminobenzaldehyde in acid solution, for which the following reaction (Scheme 2) is given,(23a) being presumably intended... 

Squaraines can be readily synthesized via the reaction of squaric acid (Treibs and Jacob, 1965) or its diester (Law and Bailey, 1986) with aromatic amines. For photoreceptor applications, Law and Bailey (1987) reported that the best results were obtained with squaraines prepared via the diester. This has been ascribed to the formation of a different crystal modification with lower impurity concentrations. Other purification methods have been reported by Lin and... 

Examples of the use of chromium(VI) reagents to effect the allylic oxidation of alkenes to give a,3-unsaturated carbonyl compounds are very common in the literature. The reaction was first reported by Treibs and Schmidt for the allylic oxidations of a-pinene to verbenone and verbenol, of dipentene to carvone and caiveol, and of cyclohexene to cyclohexenol and cyclohexenone, using a solution of chromium trioxide in a mixture of acetic anhydride and carbon tetrachloride. However, yields were low and no synthetic use of this observation was made. 

Some other reactions involving oxidation of the C—Hg bond have been known for some time, but these are either of limited synthetic appeal or have experienced no significant development in recent years. Thus ozonolysis of the C—Hg bond to form carboxylic acids or ketones falls into the first category, whereas allylic acetoxylation of alkenes by Hg(OAc>2 falls into the second category. Nevertheless, this allylic oxidation (Treibe s reaction) has considerable synthetic utility, and has been reviewed quite recently.5 ... 

Acetoxylation. Treibs found that olefins and ketones can be acetoxylated by reaction with mercuric acetate. Initially the reaction was conducted without solvent... 

Treibs found" that the reagent reacts with an aliphatic acid bromide in carbon tetrachloride, at a bath temperature raised from 100 to 135°, with introduction of COBr into the o -position. The reaction can be followed by absorbing the hydrogen... 

This we take as a reasonable premise, given the structural complexity of this class of biomarkers hee Figure 1), and was concluded years ago by the late Professor Alfred Treibs (1-5). However, the development of strong precursor-product relationships in organic geochemistry requires not only statement of plausible end-members (e.g. chlorophyll-a and DPEP-series geoporphyrins) but must include description of the intervening reactions and intermediate structures. 

Mass spectra of one such isolate (Figure 2) reveals that diagenetic dealkylation has occurred. That is, at temperatures below that required for the tetrapyrrole aromatization reaction (e.g. 20-30°C. 4-5),thermal (viz. catagenetic) dealkylation is hardly likely. Thus, the presence of carbon numbers below C-32, the expected product of Treibs Scheme geochemistry (1,6-7). most likely reveals methylene-equivalency losses related to defunctionalization during early diagenesis. The intervention of sedimentary bacterial Infauna is theoretically possible and is being studied. 

To the submitter s knowledge the synthesis of 5,15-diphenylporphyrin has been reported on only two previous occasions. Both syntheses relied on the reaction of dipyrromethane, a relatively air-sensitive compound, with benzaldehyde. Treibs and... 

Kuhlberg, Ann. 163, 123 (1872) von Miller, Ann. 188, 196 0877). Synthesis (Perkin reaction) Irom benzaldehyde, aoe-tic anhydride, and potassium acetate Org. Reactions 1, 248 (1942) from oxalyl bromide + styrene Treibs et aL, NatUr-wiss. 45, 85 (1958) from acetylene + benzaldehyde Her-betz, Her. 92, 541 (1959). Prepn of cis- and traui-isomers Comte et at. Compt. Rend. 245, 1144 (1957). lsoln from wood-rotting fungus, Stereum subpileatum Berk. St Curt. Birkinshaw et at, Biochem. J. 66, 188 (1957). 

Vanadium(v) oxide and hydrogen peroxide are used in anhydrous tert-butyl alcohol, dilute methanol, or acetone solution. Experiments by Treibs and his collaborators135,136 showed that these reactions are unspecific since oxidation occurs at the allylic position as well as the desired hydroxylations. 

Squaric acid undergoes condensation reactions with a variety of nucleophiles to form 1,3-disubstituted products possessing intense absorption in the visible and near-infrared region [7-11]. Schmidt [12] has proposed the widely accepted name squaraine for this class of dyes which was first reported by Treibs and Jacobs [7]. A major part of the earlier work on the synthesis of squaraines was carried out by the former group [7,13] and by Sprenger and Ziegenbein [14-16]. Later, Law and coworkers have contributed extensively to the synthesis of unsymmetric squaraines [17-20]. More recently, Nakazumi et al. [21] have reported a new class of cationic squaraines. 

The major metalloporphyrin in petroleum and oil shale is vanadyl deoxo-phylloerythroetioporphyrin (VODPEP) which was first discovered by Alfred Treibs (of the same Munich school of porphyrin chemistry as Hans Fischer) in 1934. Treibs quickly realised that his discovery strongly implied a biological origin for coal and oil. But he went further and developed a scheme of chemical (as opposed to biochemical) reactions that could have occurred to convert chlorophyll in green plants into VODPEP. 

The classic reaction between alkylmagnesium halides and carbon disulphide has been used recently in connection with the preparation of some simple dithio-acids. Treibs and Friess have reported on the utility of carbon disulphide in Friedel-Crafts syntheses. Thus, treatment of 2-methyl-3-ethoxycarbonylpyrrole and 3,5-dimethyl-2-ethoxycarbonylpyr-role with carbon disulphide in the presence of excess aluminium chloride gave the dithio-acids (249) and (250), respectively, but in relatively low... 

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