Design and Synthesis of Cyclic Dinucleotide Analogues Containing Triazolyl C-Nucleosides.

Natural cyclic dinucleotide (CDN) is the secondary messenger involved in bacterial hemostasis, human innate immunity, and bacterial antiphage immunity. Synthetic CDN and its analogues are key molecular probes and potential immunotherapeutic agents. Several CDN analogues are under clinical research for antitumor immunotherapy. A myriad of synthetic methods have been developed and reported for the preparation of CDN and its analogues. However, most of the protocols require multiple steps, and only one CDN or its analogue is prepared at a time. In this study, a strategy based on a macrocyclic ribose phosphate skeleton containing a 1'-alkynyl group was designed and developed to prepare CDN analogues containing triazolyl C-nucleosides by click chemistry. Combinatorial application of click chemistry and the sulfenylation cascade to the macrocyclic skeleton expanded the diversity of the CDN analogues. This macrocyclic skeleton strategy rapidly and efficiently provides CDN analogues to facilitate research on microbiology, immunology, and immunotherapy.