A New and Easy Synthesis of Silylated Furanoid Glycals in One Step from Nucleosides

New Uses for the Burgess Reagent in Chemical Synthesis: Methods for the Facile and Stereoselective Formation of Sulfamidates, Glycosylamines, and Sulfamides

“…As these investigations have revealed, the Burgess reagent (1) and its relatives (48)(49)(50)(51) are notably effective at accomplishing a number of non-dehydrative synthetic tasks when applied to appropriate substrates, such as the formation of sulfamidates from 1,2-diols or epoxyalcohols, a-and b-glycosylamines from carbohydrates, and cyclic sulfamides from 1,2-aminoalcohols. In each case, the synthetic approach is a marked improvement over those currently in the literature and should extend the potential of these synthons as tools for chemical biology, ligands for asymmetric synthesis, or starting materials for a variety of other applications.…”

“…[19] This result was unexpected, as 1 is known to be both thermal and moisture sensitive, [2a] features which might be modulated by differentiation of the carbamate portion. In any case, as shown in Scheme 4, we found it quite easy to prepare four different Burgess-type reagents (48)(49)(50)(51), representing an orthogonal set of amine-protecting groups (based on deprotection by hydrogenation, photolysis, exposure to palladium-based catalysts, or treatment with Zn, respectively) by treating chlorosulfonylisocyanate (43) with the alcohol of interest and then exposing the resultant product to Et 3 N. [20] Now the question was whether these reagents would perform with equal facility as 1 in sulfamidate synthesis. Pleasingly, the answer was yes as their exposure to several diol substrates resulted in the formation of the desired sulfamidate products (52-60, Table 3) in comparable efficiency and selectivity as observed previously with 1.…”

“…[48] The resultant product was then dihydroxylated in a manner similar to the preparation of 71 to give diol 81 (0.378 g, 88 % yield) as a white amorphous solid. R f = 0.…”

Synthesis of a dA-dT Base Pair Analogue and Its Effects on DNA-Ligand Binding

“…For the dm 3 2P derivative we chose to prepare a protected version of a 5-iodo-2-pyridone derivative (4, Scheme 1) and using a Heck reaction (17), couple the heterocycle to the 1,2-dideoxy glycan (9). The glycan itself was prepared from dT with a bulky silyl protecting group on the 3Ј-hydroxyl (7, Scheme 2) and then the requisite double bond was introduced by elimination of the heterocycle (→ 9) in refluxing HMDS (Scheme 2)-similar to a previously described procedure (18). The bulky 3Ј-protecting group ensured that the heterocycle was added by a Heck reaction in such a manner that only the ␤-nucleoside (10) resulted (Scheme 1).…”

A Convenient Synthesis ofN,N′-dibenzyl-2,4-diaminopyrimidine-2′-deoxyribonucleoside and 1-Methyl-2′-Deoxypseudoisocytidine

“…[2][3][4][5] In this regard, C-glycosides have been of particular interest to our work since they are robust with respect to chemical degradation and analogs of natural nucleotides (e.g., formycin A for adenosine, Procedures for the synthesis of these glycals have been reported in the literature. [17][18][19] Glycal 1 was synthesized in five steps while 2 was synthesized in two steps from thymidine following procedures reported by Cameron et al [19] There are several reports in the literature of Heck coupling reactions that were successful without protection of the exocyclic primary amines of the aglycon. [20][21][22][23][24] The reports inspired the investigation of the Heck coupling of the aglycon 4 with each of the glycals 1 and 2 to produce 5 and 6, respectively.…”