title: Synthesis of Morpholino Monomers, Chlorophosphoramidate Monomers, and Solid-Phase Synthesis of Short Morpholino Oligomers.
abstract: Phosphorodiamidate morpholino oligomers (PMOs) are a highly capable class of synthetic antisense oligonucleotides that are used to study gene functions in in vitro and in vivo models. This unit describes the synthesis of exocyclic-amine-protected 7'-hydroxy and 7'-chlorophosphoramidate-activated morpholino monomers of A, T, G, and C, together with their incorporation into short PMO oligomers by solid-phase synthesis. Starting from ribonucleosides, the exocyclic-amine-protected 7'-hydroxy monomers are prepared following a modified Summerton protocol, which consists of a periodate cleavage/Schiff base formation/reduction cycle. The exocyclic amine protections are installed at a later stage (except G) to avoid the use of costly exocyclic-amine-protected counterparts that give control over protecting group manipulation. The 7'-hydroxy monomers with N-Trit/N-MMTr are then converted to the 7'-chlorophosphoramidate morpholino monomers in one step employing a combination of lithium bromide and DBU. These chlorophosphoramidate monomers are finally assembled by solid-support synthesis to obtain the short PMO oligomers.
authors.affiliation: Department of Organic Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata, India.|These authors contributed equally.
authors.forename: Jhuma
authors.initials: J
authors.lastname: Bhadra
authors.affiliation: Department of Organic Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata, India.|These authors contributed equally.
authors.forename: Sankha
authors.initials: S
authors.lastname: Pattanayak
authors.affiliation: Department of Organic Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata, India.
authors.forename: Surajit
authors.initials: S
authors.lastname: Sinha
mesh_terms: D060172:Morpholinos / Q000138:chemical synthesis / Q000737:chemistry*; D009841:Oligonucleotides / Q000737:chemistry*; D016376:Oligonucleotides, Antisense; D060327:Solid-Phase Synthesis Techniques
chemical_list: D060172:Morpholinos; D009841:Oligonucleotides; D016376:Oligonucleotides, Antisense
keywords: antisense compounds; chlorophosphoramidate; morpholinos; oligonucleotides; phosphorodiamidate morpholino oligonucleotides (PMO); solid-phase synthesis