Synthesis of 8-(2′-deoxy-β-d-ribofuranosyl)imidazo[1,2-a]-s-triazin-4-one

anti-syn Unnatural Base Pair Enables Alphabet-Expanded DNA Self-Assembly

Self-assembly properties and diversity in higher-order structures of DNA enable programmable tools to be used to construct algorithms at the molecular level. However, the utility of DNA-based programmable tools is hampered by the low orthogonality to natural nucleic acids, especially in complex molecular systems. To address this challenge, we report here the orthogonal regulation of DNA self-assembly by using an unnatural base pair (UBP) formation. Our newly designed UBP An^N:Sy^N is formed in combination with anti and unusual syn glycosidic conformation with high thermal stability and selectivity. Furthermore, An^C worked as a pH-sensitive artificial nucleobase, which forms a strong base pair with cytosine under a weak acidic condition (pH 6.0). The orthogonal An^N:Sy^N base pair functioned as a trigger for hybridization chain reaction to provide long nicked double-stranded DNA (ca. 1000 base pairs). This work represents the first example of the orthogonal DNA self-assembly that is nonreactive to natural four-letter alphabets DNA trigger and expands the types of programmable tools that work in a complex environment.

A one-pot, multicomponent reaction for the synthesis of novel 2-alkyl substituted 4-aminoimidazo[1,2-a][1,3,5]triazines

A highly selective, one-pot, three-component synthesis of novel 2-alkyl-substituted 4-aminoimidazo[1,2-a][1,3,5]triazines has been developed. The scope of the method was explored in two dimensions, varying the structures of trialkyl orthoesters and 2-aminoimidazoles in their reactions with cyanamide. Conveniently performed under microwave irradiation, this method was also proved to be efficient under conventional heating. A library of 24 novel compounds was prepared in high purity using this multicomponent approach. Molecular and crystal structures of representative molecules were studied using X-ray crystallography.

A multicomponent reaction of 2-aminoimidazoles: microwave-assisted synthesis of novel 5-aza-7-deaza-adenines

An efficient and highly selective multicomponent synthesis of 4-aminoimidazo[1,2-a]triazines, which are 5-aza-7-deaza-isosteres of adenine, was developed.

Synthesis of 7-aza-5-deazapurine analogues via copper(I)-catalyzed hydroamination of alkynes and 1-iodoalkynes

A new method for the synthesis of dihydroimidazo[1,2-a][1,3,5]triazin-4(6H)-ones via copper(I)-catalyzed hydroamination was developed. In addition, for the first time, iodoalkynes were shown to participate in the copper(I)-catalyzed intramolecular hydroamination reaction with exclusive formation of E-isomers.

X-ray structure of 1,3,4-tri-O-acetyl-2-deoxy-beta-d-erythro-pentopyranose

Peracetylated 2-deoxy-d-erythro-pentose (2-deoxy-d-ribose) was synthesized through the acetylation of 2-deoxy-d-ribose with acetic anhydride in pyridine, and the products (including all four ring forms) exist in form of either a white solid or a syrup. A single crystal of 1,3,4-tri-O-acetyl-2-deoxy-beta-d-erythro-pentopyranose was obtained from the syrup and its structure was determined by X-ray diffraction. The crystal adopts the (1)C(4) conformation, presenting an orthorhombic system, space group P2(1)2(1)2(1) with Z=4, unit cell dimensions a=7.2274 (3)A, b=8.0938 (5)A, and c=22.0517 (11)A.