TNAs [(L)-alpha-threofuranosyl oligonucleotides] containing vicinally connected (3'-->2') phosphodiester bridges undergo informational base pairing in antiparallel strand orientation and are capable of cross-pairing with RNA and DNA. Being derived from a sugar containing only four carbons, TNA is structurally the simplest of all potentially natural oligonucleotide-type nucleic acid alternatives studied thus far. This, along with the base-pairing properties of TNA, warrants close scrutiny of the system in the context of the problem of RNA's origin.

Dieter Seebach zum 65. Geburtstag gewidmet Our studies of a-l-Threofuranosyl-(3' 3 2')-oligonucleotides (−TNA×) are part of a systematic experimental inquiry into the base-pairing properties of potentially natural nucleic acid alternatives taken from RNA×s close structural neighborhood. TNA is an efficient Watson-Crick base-pairing system and has the capability of informational cross-pairing with both RNA and DNA. This property, together with the system×s constitutional and (presumed) generational simplicity, warrants special scrutiny of TNA in the context of the search for chemical clues to RNA×s origin.

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Total synthesis concepts for the preparation of deoxygenated hexoses which are constituents of many secondary metabolites with antibacterial and antitumor activity are surveyed.