Mono-tert-butyl

Lack of reactivity towards SN2 reactions at nitrogen would in itself account for low mutagenic activity. However, the tert-butyl groups on 31c f and 32a,b are well removed from the reactive nitrogen and, as well, SN2 reactions of mutagens 31c e with A-methylaniline in methanol at 303 °C occur with relatively similar rate constants to that of unsubstituted 28a, and of mono tert-butylated systems 28i and 31 a,b (Table 18). 

On the basis of molecular modeling studies, MacMillan et al. optimized their original amine catalyst 42 to the mono-tert-butylated structure 45 [31]. As summarized in Scheme 4.16, this catalyst enables highly enantioselective 1,4-addition of... 

N1 - PHTHALIC ACID, MONO-Tert-BUTYL ESTER, AMMONIUM SALT... 

A simple one-pot procedure for the synthesis of Fmoc-protected aspartic and glutanoic acid tert-butyl esters is shown in Scheme tert-Butylation of unprotected Asp and Glu can be effected in dioxane with excess isobutene using 4-toluenesulfonic add as catalyst. Subsequent Fmoc derivatization results in a mixture of the mono-tert-butyl esters (co/a 65/35 for Glu and 50/40 for Asp) with an overall yield of 55-60% contaminated with small amounts of d -tert-butyl esters. This procedure has the advantage that the Fmoc group is introduced without prior isolation or purification of the aspartic and glutamic tert-butyl esters. Whilst the diesters are readily removed by extraction with organic solvents, the Fmoc-Asp/Glu(OtBu)-OH derivatives are isolated by crystallization from dichloromethane/petroleum ether. 

C7H1202 5-methyl-2-hexenoic acid 41653-96-7 499.65 43.850 1,2 11557 C7H1204 mono-tert-butyl malonate 40052-13-9 464.16 40.452 2... 

In the reactions described the tert-butyl group survives comparatively drastic conditions although as might be expected the use of aluminium chloride sometimes causes de-tert-butylation.Thecompound2,4-di-tert-butyl-6-(5-chloro-pyridazin-2-yl)methylphenol in dichloromethane with aluminium chloride (3 equivs.), upon stirring at ambient temperature for 15 mins, followed by careful work-up of the mixture by quenching with water over 30 mins, gave the 4-mono tert-butyl product in 73% yield (ref.98). 

It is of interest that mixtures of 3- and 4-methylphenols are usually employed for the preparation of the di-tert-butyl compounds, namely, 4-methyl-2,6-di-tert-butylphenol and 5-methyl-2,4-di-tert-butylphenol from the butylation reaction which is carried out at 40-50°C and atmospheric pressure with sulphuric add (2%) as the catalyst. t-Butylation occurs ortho to the hydroxyl group. The products are separable by fractional distillation into the pure compounds. 2,4-and 2,5-Xylenols are employed as a mixture to provide, under the same reaction conditions, a source of the required 2,4-dimethyl-6-tert-butylphenol which has an important use as a stabiliser in petroleum fuels. The products from the reaction with iso-butene are procesed to remove alkali-soluble unchanged 2,5-xylenol together with the mono tert-butyl derivative and the alkali-insoluble 2,4-dimethyl-6-tert-butylphenol is recovered by distillation... 

The alkylation of biphenyl with /ert-butanol has been carried out over different zeolites under liquid phase conditions. HM (17.5) and HY (15) zeolites have been found to be the most active, with a maximum biphenyl conversion near 60 %. Dealuminated mordenite HM (17.5) leads to very high selectivities to 4-(ter/-butyl)biphenyl (99%) and 4,4 -di(/er/-butyl)biphenyl (96%). Selectivity to linear 4-TBB and 4,4 -DTBB depends on diffusional possibilities of relatively voluminous mono tert-butyl- and di (rert-butyl)biphenyl isomers from the zeolite pores. The most suitable temperature has been found to be 160 "C. An increase of the temperature leads to a significant decrease of selectivities to the desired products, as a result of secondary reactions. 

The 5-O-methyl analc e of bufotenine (5-MeO-DMT) is parenterally active as a hallucinogen in humans, but is not orally active. 5-MeO-DMT exhibits similar psychological and somatic symptoms in humans as DMT, but is approximately an order of magnimde more potent on a milligram basis (see Table III). Both 5-MeO-DMT and bufotenine are closely related stmcturally to the CNS transmitter serotonin (5-hydroxytryptamine). The N,N-diisopropyl analogues of DMT and 5-McO-DMT are both orally active as hallucinogens in humans (Shu%in Carter 1980). Little is known of the hallucinogenic activity of the N-monosubstituted, N-dealkyl or N-cyclo-alkyl tryptamines. The mono-tert-butyl derivative is reputed to be orally active (Shubin 1982). 

Mp 21-22°. Bp5 175°. [a]g +11.5 (neat). Mono-teti-butyl ester Mono-tert-butyl tartrate [210056-53-4]... 

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