A new type of silyl protecting group was designed and a reagent for its introduction was obtained. This reagent, 1,3--dihalo-1,1,3,3-tetraalkyldisiloxane, allows simultaneous protection of 3′-OH and 5′-OH groups of nucleoside in high yield. The properties of the new protecting group were studied and some aspects of its applications are presented.

Zinc/acetylacetone/pyridine treatment has been designed as a very efficient method for removal of 2,2,2-trichloroethyl group from phosphoesters. Internucleotide and terminal 2,2,2-trichloroethyl phosphotriesters were transformed to corresponding diesters quantitatively. Much less reactive 2,2,2-trichloroethyl phosphodiesters produced monoesters with Ca. 90% yield.

The problem addressed in this paper is concerned with DNA sequencing by hybridization. An algorithm is proposed that solves a computational phase of this approach in the presence of both positive and negative errors resulting from the hybridization experiment. No a priori knowledge of the nature and source of these errors is required. An extensive set of computational experiments showed that the algorithm behaves surprisingly well if only positive errors appear. The general case, where positive and negative errors occur, can be also solved satisfactorily for an error rate up to 10%.

2′,3′,5′-Tri-O-acetylguanosine (1b) reacts with 2,6-dichlorobenzoyl and mesitylenesulphonyl chlorides to give the corresponding crystalline O(6)- acyl derivatives [(2) and (3a), respectively].

1,3-dichloro-1,1,3,3-tetraisopropyldisiloxane (I) reacts with cytosine arabinoside (II) in pyridine under the formation of 3',5'-O-(tetraisopropyldisiloxane-1,3-diyl)cytosine arabinoside (IIIa) and with 1-(6'-deoxy-α-L-talofuranosyl)uracil (V) under the formation of 2',3'-O-(tetraisopropyldisiloxane-1,3-diyl) 1-(6-deoxy-α-L-talofuranosyl)uracil (VIa).