Tcrf-Butyl group

However, when a thiocarbonimidate prepared from an acyclic allylic alcohol underwent cyclization, no significant relative 1,2-asymmetric induction was observed [d.r. (cis/trans) 58 42], Structural assignment of the diastereomeric mixture was made by removal of the tcrf-butyl group with trifluoroacetic acid to give 6, followed by cleavage of the C —Br bond with tributyltin hydride, since the stereochemistry of both cis- and rr[Pg.840]

In each of these problems, a fcrt-butyl group is the larger substituent and will be equatorial in the most stable conformation. Draw a chair conformation of cyclohexane, add an equatorial tcrf-butyl group, and then add the remaining snbstiment so as to give the required cis or trans relationship to the teri-bntyl gronp. 

The checkers obtained 12.8-13.0 g. (52-53%), m.p. 84-86°, in the first crop and 2.7-3.4 g. (11-14%), m.p. 52-62°, in the second crop. Recrystallization of the former from methanol gave 11.5 g. of crystals, m.p. 84-86°, suggesting that the first crop is a pure single isomer. A proton magnetic resonance spectrum in chloroform-d of the second crop shows two singlets at 8 1.62 and 1.64 for the terf-butyl groups. Thus this material is a mixture of syn and anti isomers. Both the first and second crops proved equally useful for tcrf-butoxycarbonylation of an amino acid. 

REMOVAL OF N -BENZYLOXYCARBONYL GROUPS FROM SULFUR-CONTAINING PEPTIDES BY CATALYTIC HYDROGENATION IN LIQUID AMMONIA O-tcrf-BUTYL-L-SERYL-S-tert-BUTYL-L-CYSTEINE ferr-BUTYL ESTER... 

Removal of rcrt-butyl groups from carbazole ring positions by strong acid or Lewis acid catalysis has been used to transform 2-tert-butyl-, 2-tert-butyl-4-methyl-, 7-tm-butyl-4-methyl-, ° 2,7-di-tm-butyl-, ° and 2,7-di-fert-butyl-4-methylcarbazoles into carbazole and 4-methylcarbazole, respectively. 1,3,6,8-Tetra-tcrf-butylcarbazole partially dealkylates with concentrated sulfuric acid at room temperature to give a mixture of 1,3,6-tri-and 3,6-di-terf-butylcarbazoles. 1-Methylcarbazole loses its substituent at... 

Approximately 15% of the photolysed hydroperoxide groups are reported to undergo a )5-scission reaction [383]. Several low molecular peroxides such as tert-amyl hydroperoxide, di-tcrf-butyl peroxide, 1,1-dienonylethyl hydro-... 

Amino groups are often protected as their tcrf-hutoxycarbonyl amide, or Boc, derivatives. The Boc protecting group is Introduced b)" reaction of the amino acid with di-Avt-butyl dicarbonatc in a nucleophilic acyl substitution reaction and is removed by brief treatment with a strong organic acid such as trifluoro-acetic acid, Cr3C02H. 

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