Trichloromethyl-substituted

Benzimidazole, l-methyl-2-trichloromethyl-substitution reactions, 5, 432 Benzimidazole, naphthoyl-, 1, 327 Benzimidazole, 5-nitro-alkylation, 5, 390 Benzimidazole, 6-nitro-1-oxide... 

Trichloromethyl substituted thiazolidines have been prepared from chloral. Reaction of chloral with anilines afforded the corresponding imines which were then treated in situ with thioglycolic acid to give a series of 2-trichloromethyl substituted thiazolidinones <96HC227>. 

Direct interception of the initially formed bicyclic oxyallyl zwitterion derived from cyclohexadienones is difficult, due to its facile rearrangement to cyclopropyl ketone. One notable exception is the observation that 4-trichloromethyl-substituted dienone 94 gave solvent adduct 97 when irradiated in methanol, and both 97 and 98 upon irradiation in acidic methanol (Scheme 24)48. It was proposed that 97 arises either from a facile... 

Dialkyl trichloromethyl(substituted amino)methylenemalonates (370) were prepared in 91-92% yields in the reactions of malonates (369) and sodium rm-butyl peroxide in aqueous ethanol at room temperature for 1-1.5 hr (83ZOB2152). 

It is also possible to eliminate chloroform from trichloromethyl-substituted heterocycles. For example, A, iV -diphenyl-l,2-diaminoethane reacts with chloral to form l,3-diphenyl-2-(trichloromethyl)imidazolidin which loses one molecule of chloroform upon heating [Eq. (21)]. The l,3-diphenylimidazolidin-2-ylidene... 

Recently it was found that ot-trichloromethyl carbinols and their ethers, a class of compounds which is easily obtainable in large structural variety, can be reduced by chromium(II) chloride in water or aqueous DMF to synthetically very interesting products (Table 5, No. 6-8) . Thus, trichloromethyl-substituted secondary alcohols and ethers give (Z)-configurated vinyl chlorides in one step (Eqs. (70)-(72)). 

Heterocyclization of aliphatic trichloromethyl-substituted compounds 93KGS980. 

Reactions of trichloromethyl-substituted 1,3-dielectrophiles 551 with hydrazine afforded hydroxy pyrazoles 552 (Equation 111) <2002TL5005>. Cyclocondensation of alkenones 553 with phenylhydrazine under microwave irradiation furnished 5-trichloromethyl-substituted pyrazoles 554 in excellent yields (Equation 112) <2003TL6669>. 4-Alkoxy-l,l,l-trichloro-3-alken-2-ones were useful precursors for the regiospecific synthesis of 5-trichloromethylpyr-azoles using hydrazines <2002SC419, 2002SC1585>. l,l,l-Trifluoro-4-ethoxy-3-buten-2-one, 3-trifluoroacetyl-3-buten-... 

A Haloform-type reaction occurs between trichloromethyl-substituted 1,3-diketones and hydrazine or. N-methylhydroxylamine to afford hydroxypyrazoles (e.g., 26) and 2-methyl-3-isoxazolones, respectively.6... 

This reaction has been modified by treatment of em-trichloromethyl-substituted tertiary alcohols (generated from the nucleophilic addition of trichloromethide), e.g., CHCI3 + LHMDS) by sodium azide and an organic base (e.g., DBU) in alcohol to form a-azido ester in a one-pot manner. The resulting a-azido ester can then be selectively converted into a-azido alcohol with cold NaBH4. ... 

The process from the FMC company involves as the pivotal step an intramolecular stereoselective [2 + 1 [-cycloaddition. In a Prins reaction [94] of chloral and isobutene, followed by an isomerisation, a racemic, trichloromethyl-substituted aUyl alcohol is obtained. Reaction with the isocyanate from (R)-naphthylethyl-amine enables separation ofthe diastereomers by crystallisation. The carbamate is cleaved by trichlorosilane/triethylamine, thus permitting the recycling of the chiral auxiliary. The optically pure (R)-aUyl alcohol is reacted with diketene, to produce the / -keto-ester. After diazo transfer and basic cleavage, the diazoacetate is obtained catalysed by a copper salt, this is converted in a [2 + 1 ]-cyclo-addition into a bicyclic lactone. The Boord reaction (discovered by Cecil E. Boord in 1930) [95] finally gives (IR)-cis-permethric acid. [96]... 

The oxazolidine approach has undergone some refinement, particularly in the nature of the protecting groups used. Thus trichloromethyl-substituted oxazolidines 8.1.2 and 8.1.3 could be prepared from the debenzoyl side chain 8.1.1 and coupled directly with 7,10-ditroc-baccatin III (without the necessity of protecting the nitrogen). The resulting oxazoline was converted to the open-chain product with zinc and acetic acid and acylated to give docetaxel (296). 

Certain imidazolinium salts, particularly derivatives with bulky N,N -sah-stituents and some triazolium salts could not be deprotonated with strong bases like NaH, but a thermally induced a-elimination reaction proved successful in these cases. This approach was attempted as early as 1960 by Wanzlick and Schikora who heated C2-trichloromethyl substituted imidazolidine but could only isolate the carbene dimer (see Scheme 1.2). Enders et al. successfully heated triazoline 67 under elimination of methanol from the C5 carbon atom and formation of triazol-5-ylidene 68 (Scheme l.lOa). ... 

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