SYNTHESIS OF N-ALPHA-(PURINYL PYRIMIDINYL ACETYL)-4-AMINOPROLINE DIASTEREOMERS WITH POTENTIAL USE IN PNA SYNTHESIS/

This paper describes an approach to introduce conformational constrain t and chirality into the PNA backbone by bridging the ethylenediamine and glycine components of the same unit by a methylene group which lea ds to PNA based on 4-aminoprolyl backbone with chirality at C-4 and C- 2. The synthesis and characterisation of all four diasteroisomers with thymine (T) as the sidechain nucleobase (3a-d) and the synthesis of o ne of the stereoisomer (2S, 4R) linked to each of the four nucleobases (10-13) are described. Using these monomeric units, two model dimers (17, 18) containing four chiral centres but differing in stereochemist ry at only one site were prepared and CD data on these indicate consid erable structural differences in base stacking induced by chiral backb one among these. Copyright (C) 1996 Elsevier Science Ltd