A Related Compound

Perhaps the best-known rival to hexapheitylethane as a sterically crowded, unknown compound, is tetra-i-butylethene  

In the light of all these calculations and experiments, what can we say about hexaphenylethane The synthesis of the substituted hexapheiylethanes 9 and 10 and the calculations of Vreven and Morokuma (above) indicate that hexapheitylethane can exist. As was exhorted for tetra-r-butylethene, the search for it must and will continue [39], 

(a) A human and chemical biography of Gomberg C. Riichardt, Nachrichten aus der Chemie, 2000, 48, 904. (b) A very brief account of Gomberg s achievement and its recognition  

A very detailed account of the historical saga J. M. McBride, Tetrahedron, 1974, 30, 2009. 

A historical account oriented to the failure of Gomberg to be awarded the Nobel prize  

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Electronegative substituents m a molecule can affect acidity even when they are not directly bonded to the lomzable proton Compare ethanol (CH3CH2OH) with a related compound m which a CE3 group replaces the CH3 group... 

A related compound, the peroxohydrate of melamine, C H N, was made by Peroxid-Chemie but discontinued in the 1980s. In addition, a diperoxohydrate of the organic base DABCO is recogni2ed and has been used as an oxidant in organic chemistry, but such a system has been known to explode (101). 

As extensive as the SDBS is, don t be disappointed if the exact compound you are looking for is not there. There are, after all, millions of organic compounds. However, much of structure determination (and organic chemistry in general) is based on analogy. Finding the spectrum of a related compound can be almost as helpful as finding the one you really want. 

The reduction of 2-methyl-1,2,3,4-tetrahydro-y-carboline (92) with zinc and hydrochloric acid in the presence of mercuric chloride gives the indolenine derivative, 2-methyl-l,2,3,4,4a,9b-hexahydro-y-carbo-line (93). A related compound, 4,9b-diethyl-2-methyl-l,2,3,4,4a,9b-hexahydro-y-carboline (96), was obtained by catalytic hydrogenation of 95, which was prepared by Fischer ring closure of the phenyl-hydrazone 94. The stereochemistry of the B/C ring junction in these... 

The sedation side effect commonly observed on administration of classical antihistaminic drugs has been attributed in part to the ease with which many of these compounds cross the blood brain barrier. There have been developed recently a series of agoits, for example, terfenadine (198), which cause reduced sedation by virtue of decreased penetration into the CNS. This is achieved by making them more hydrophilic. Synthesis of a related compound, ebastine (197),... 

Pyrimidinopyrazines related to folic acid have been investigated in some detail for their antimeta-bolic and antineoplastic activities. A related compound, which lacks one nitrogen atom, has been described as an antiproliferative agent, indicating it too has an effect on cell replication. Aldol condensation of the benzaldehyde 99 with ethyl acetoacetate gives the cinnamate 100. This is then reduced catalytically to the acetoacetate 101. Reaction of that keto ester with 2,4,6- triami-nopyrimidine gives the product 102 which is subsequently chlorinated (103) and subjected to hydrogenolysls. There is thus formed piritrexim (104) [17]. 

The manufacture of a related compound is first described. 28.1 parts of p-chloro-benzhy-dryl bromide are heated to boiling, under reflux and with stirring, with 50 parts of ethylene chlorohydrin and 5.3 parts of calcined sodium carbonate. The reaction product is extracted with ether and the ethereal solution washed with water and dilute hydrochloric acid. The residue from the solution in ether boils at 134° to 137°C under 0.2 mm pressure and is p-chloro-benzhydryl-(/3-chloroethyl) ether. 

In 1987 an international treaty was signed in Montreal to cut back on the use of CFCs. Production of Freon in the United States ended in 1996. It has been replaced in automobile air conditioners by a related compound with no chlorine atoms, C2H2F4 ... 

The anion is assumed to exist preferentially in the anti conformation A, which offers a stabilizing 7rc -> minimizes steric interactions69,71 11. The nonplanar nature of the carhanionic center and coordination of the lithium to the oxygen atom could be demonstrated for a related compound by an X-ray analysis72. Usually, the electrophile attacks the carhanionic center with stereoinversion. 

Tolerance is characterized by reduced responsiveness to the initial effects of a drug after repeated exposure or reduced responsiveness to a related compound (i.e., cross-tolerance). Animal studies have not provided conclusive evidence of tolerance to the effects of the centrally active compounds in toluene or trichloroethane (Moser and Balster 1981 Moser et al. 1985). Observations in humans, on the other hand, have documented pronounced tolerance among subjects who chronically inhale substances with high concentrations of toluene (Glaser and Massengale 1962 Press and Done 1967) and butane (Evans and Raistrick 1987). Kono et al. (2001) showed that tolerance to the reinforcing effects of solvents is comparable to that conditioned by nicotine but less intense than that reported with alcohol or methamphetamine use. 

Knoevenagel condensation of diethyl malonate or related compounds with a,fi-unsaturated aldehydes and ketones results in diene esters (equation 40)78. This condensation reaction has been used to extend the polyene chain length of vitamin A related compounds (equations 4179 and 4280). 

Incubation mixtures containing calf thymus DNA resulted in senecionine and a related compound being bound to a macromolecular liver fraction (224). The binding of the compounds was dependent on the presence of oxygen, the enzyme system, and an NADPH-generating system, thus demonstrating that metabolites such as those formed from senecionine (Scheme 34) may interact with macromolecules to result in alkaloid-associated toxicities. 

A related compound in which the aryl groups and acetylide functions are both in m-arrangement has been prepared in 84% yield starting with m-[(C6F5)2Pt(TFIT)2]. Again, the compound is an acetone solvate, but the intermolecular... 

The above example clearly points to nonenzymatic hydrolysis of 3,4-dimethyl-5-phenyloxazolidine (11.106). However, enzymatic hydrolysis cannot entirely be ruled out. A related compound, 3-isopropyl-5- [(naphthalen-... 

The glycolate pipeline continued to supply new candidate agents, each one a related compound with differing properties, and they all seemed deserving of clinical evaluation. It seemed necessary to study any compound that an enemy might conceivably use against us. We felt it important to know whether any of them possessed some unique type of toxicity, requiring novel medical countermeasures. 

A related compound was prepared by the reaction of 1,2-diiodoacenaphtalene with sodium telluride under aprotic conditions. ... 

It was found that the A-protected p-nitrophenyl ester of L-Arg spontaneously cyclized into 42 (R = NO2) (61JOC3347). A related compound 42 (R = H) was obtained as a by-product in the reaction between N,N-dicarbobenzoxy-L-Arg and diethyl L-glutamate (59JA2878). 

Anodic oxidation of halogenated tyrosines was studied in connection with some sponge metabolites (cavemicolin model compounds). The methyl exter of 3,5-dibromotyrosine afforded four different products in a 41 10 26 23 ratio with 23% overall yield as a result of equilibration. (Scheme 44) [93JCS(P2)3117], A related compound was obtained as a mixture of stereoisomers 56 from a Diels-Alder reaction between N-acetyldehydroalanine methyl ester and l-methoxy-l,3-cyclohexadiene (87TL2371). 

In connection with the enantioselective alkylation of Pro or 4-hydroxy-proline, the azabicyclo[3.3.0]octane system 81 was obtained after reaction with pivaldehyde (81HCA2704 85HCA155). In a more complex transformation A-protected L-Pro was transformed into the same bicyclic system (Scheme 49) (81JA1851 84JA4192). The product was prepared as a model substance in the total synthesis of pumiliotoxin. A related compound 82 was prepared from 5-(hydroxymethyl)-2-pyrrolidinone (prepared from L-pyroglutamic acid) by an acid-catalyzed condensation with benzaldehyde (86JOC3140). 

Tolbutamide (Figure 7.8) is metabolized via the benzylic methyl group by CYP2C9 as the major clearance mechanism. Chlorpropamide is a related compound incorporating a chlorine function in this position. The resultant metabolic stability gives chlorpropamide a lower clearance and a longer half-life (approximately 35 h compared to 5 h) than tolbutamide, resulting in a substantial increase in duration of action [5]. 

Dimercaprol (BAL, British Anti-Lewisite) was developed in World War 11 as an antidote against vesicant organic arsenicals (B). It is able to chelate various metal ions. Dimercaprol forms a liquid, rapidly decomposing substance that is given intramuscularly in an oily vehicle. A related compound, both in terms of structure and activity, is di-mercaptopropanesulfonic acid, whose sodium salt is suitable for oral administration. Shivering, fever, and skin reactions are potential adverse effects. 

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