TFAA

Ethyl indole-2-carboxylate 4-Methoxybenzoic acid, TFAA, H3PO4 74 [11]... 

CF3COOH, TFAA, CH2CI2. These conditions afford the trifluoroacetate, thus preventing retritylation, which is sometimes a problem when a trityl group is cleaved with acid. A further advantage of these conditions was that a SEM group was completely stable. When TFAA was not used. 

Nicolaou in his model system for an approach to the thiopeptide antibiotic thiostrepton, in particular, the elaboration of the quinaldic acid moiety. The tetrahydroquinoline 21 was converted to the A-oxide by /n-CPBA oxidation. Subsequent treatment with TFAA, to carry out the Boekelheide reaction, was followed by hydrolysis of the resultant ester to produce 22 as a mixture of alcohols. 

An approach to the construction of Fe(II)-binding agent pyrimine 40, isolated from Pseudomonas species, employed the bis-homophenylalanine 38. Initiation of the Boekelheide reaction with TFAA and hydrolysis gave the advanced intermediate 39 that provided access to the natural product. 

The trifluoromethyl derivative 146 has been obtained as a minor product from the reaction of (l-methyhndol-3-yl)methanol with trifluoroacetic acid anhydride (TFAA), the major product (22% yield) being 6-trifluoromethylindolo[3,2-()]-carbazole [98LTC(B)841]. Several substituted indolo[2,3-()]carbazoles have also been encountered during studies on the reaction of 4,6-dimethoxyindole with... 

Similarly, iV,A/ -dimethyl-3,3 -bisindolylmethane (169) has been used in a related experiment, where treatment thereof with trifluoroacetic fflihydride (TFAA) in diethyl ether at room temperature yielded a mixture of products from which the trifluoromethyl-substituted indolo[3,2-b]carbazole 170 was isolated as the major pentacyclic component, accompanied by the hydroxy derivative 171 as well as small amounts of the indolo[2,3-h]carbazole 146 (Scheme 20). The precursor 169 could also be prepared in situ from A-methylindol-3-methanol under... 

When 2-lithio-2-(trimethylsilyl)-l,3-dithiane,9 formed by deprotonation of 9 with an alkyllithium base, is combined with iodide 8, the desired carbon-carbon bond forming reaction takes place smoothly and gives intermediate 7 in 70-80% yield (Scheme 2). Treatment of 7 with lithium diisopropylamide (LDA) results in the formation of a lactam enolate which is subsequently employed in an intermolecular aldol condensation with acetaldehyde (6). The union of intermediates 6 and 7 in this manner provides a 1 1 mixture of diastereomeric trans aldol adducts 16 and 17, epimeric at C-8, in 97 % total yield. Although stereochemical assignments could be made for both aldol isomers, the development of an alternative, more stereoselective route for the synthesis of the desired aldol adduct (16) was pursued. Thus, enolization of /Mactam 7 with LDA, as before, followed by acylation of the lactam enolate carbon atom with A-acetylimidazole, provides intermediate 18 in 82% yield. Alternatively, intermediate 18 could be prepared in 88% yield, through oxidation of the 1 1 mixture of diastereomeric aldol adducts 16 and 17 with trifluoroacetic anhydride (TFAA) in... 

DPC dipyridine chromium(vi) oxide TFAA trifluoroacedc anhydride... 

Triphenyl-4f/-selenopyran (12b) disproportonated into a mixture of tetrahydro derivative 155a and perchlorate 156a after initial treatment with TFAA and then with HC104 (84KGS1634). An attempt to prepare... 

R3 = Me) - 151 (R = H, R = Ph). The reductions proceed via a 3,5-protonation of the 4//-thiopyran ring as follows from experiments with 132(R, R2,R3 = H, Ph, H Me, Ph, H) using the deuterium-labeled TESH or TFAA (83KGS200, 83MI2). In some cases HC104 instead of TFAA could be used (83KGS200). 

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