Trichloroacetyl group

Anhydro-D-glucose results from the action of anhydrous ammonia on l-chloro-2-trichloroacetyl-D-glucose triacetate (Brigl s compound73 8) and the preferential formation of an ethylene oxide ring is undoubtedly due to the lability of the trichloroacetyl group in position 2. 

Little is known about transition metal catalyzed epoxidation of simple allylic amides. The easily removable trichloroacetyl group is suitable as /V-substituent in the molybdenum-catalyzed epoxidation of (Z)-allylic systems with rm-butyl hydroperoxide, which produces the. sv -com-pound with appreciable selectivity21. 

The biomimetic total synthesis of (+)-20-epiervatamine was accomplished by J. Bosch et al. The authors used the addition of 2-acetylindole enolate to a 3-acylpyridinium salt as akey step to connect the two main fragments. The in situ formed 1,4-dihydropyridine was trapped with trichloroacetic anhydride to afford the corresponding trichloroacetyl-substituted 1,4-dihydropyridine derivative. The conversion of the trichloroacetyl group to a methyl ester was achieved by treatment with sodium methoxide. This transformation can be regarded as the second step of the haloform reaction. 

Deprotection of 11.85, 11.86, and 11.87 was carried out as follows. Conversion of the A-trichloroacetyl groups to the corresponding A-acetyl groups was achieved by treatment with tributylstannane and azoisobutylnitrile (AIBN) to give the corre-... 

Lactaldehyde 689 has been used as the chiral source in an interesting synthesis of unnatural D-threonine (695) [204] (Scheme 93). The first of the two most important reactions in the sequence is the conversion of 691 to 692. The transformation proceeds by partial methano-lysis of the trichloroacetyl group followed by intramolecular conjugate addition, which forms the oxazolidinone ring in 692 stereospecifically at C-4 and C-5. The second critical reaction is a Pummerer rearrangement of 693 to 694, which introduces the requisite carboxyl function (as... 

Tri-O-acetyl-a-D-glucopyranosyl azide (189), obtained from Brigl s chloride (3,4,6-tri-(9-acetyl-2-trichloroacetyl-p-D-glucopyranosyl chloride) by selective removal of the trichloroacetyl group has long been the only representative of this class of compounds. 

Reaction of j8-maltotriose hendeca-acetate with phosphorus pentachloride afforded 2, 2",3,3, 3",4",6,6, 6"-nona-0-acetyl-2-(9-trichloroacetyl- -maltotriosyl chloride (42%), which could be isomerized (TiCh in chloroform) to the corresponding a-chloride. 2 Selective ammonolysis of the trichloroacetyl group in the a- and jS-chlorides gave the 2-hydroxy derivatives. 

---