Iodosobenzene Diacetate and Diphenyl Diselenide: An Electrophilic Selenenylating Agent of Double Bonds

Ring‐Closure Reactions through Intramolecular Displacement of the Phenylselenonyl Group by Nitrogen Nucleophiles: A New Stereospecific Synthesis of N‐Tosyl and N‐Benzoyl‐1,3‐oxazolidin‐2‐ones from β‐Hydroxyalkyl Phenyl Selenides

“…The starting b-hydroxyalkyl phenyl selenides 6 a, [25] 6 c, [26] 6 d, [27] 6 f, [27] 6 m, [28] 11 a, [29] 11 c, [27] 11 d, [27] 11 g, [27] and 19 a [26] were prepared as described in the literature. Compounds 11 b and 11 f were obtained by regioand stereospecific hydroxyselenation of the corresponding allylic ethers [30] using phenylselenyl chloride.…”

New oxidative transformations of alkenes and alkynes under the action of diacetoxyiodobenzene

“…For instance, the oxidation of (E) stilbene (13) with the DIB-H 2 SO 4 system was nonselective and gave a mixture of compounds 3c, 8c, 9c, and 10b-12b (see Table 1, entries [13][14][15]. This fact is explained by the poor solubil ity and low nucleophilicity of (E) stilbene.…”

Elimination reactions of glycosyl selenoxides

“…3 In order to investigate the relative rates of the possible nucleophilic substitution versus elimination reactions the selenoglycoside 2a was subjected to oxidation under the standard conditions at 0 8C in the presence of 10 equiv of methanol. Under these reaction conditions no methyl glycoside was obtained, the only product being the expected glycal 2b, which was isolated in quantitative yield.…”

“…Since selenoxides undergo thermal elimination at considerably lower temperatures than sulfoxides 13 such a spontaneous elimination of a glycosyl selenoxide would advantageously obviate the need for isolation of any intermediates, and also eliminate the possibility of over-oxidation, which can be problematic in the case of glycosyl sulfoxides. Following a previous report on the use of glycosyl selenoxides as glycosyl donors 3 it was also decided to investigate the potential fate of glycosyl selenoxides if the 2-hydroxyl or 2-amino group was cis to the anomeric selenium, since in this case syn elimination would not be possible (Fig. 1).…”

“…2 However, the chemistry of glycosyl selenoxides has not yet been the focus of extensive investigation. 3 As part of ongoing studies into expanding the synthetic utility of glycals 4-6 as starting materials for the synthesis of a variety of C-glycosides 7 we sought easy access to a wide range of 2-hydroxy and 2-amino substituted materials. Since existing synthetic routes to 2-hydroxy glycals are not particularly high yielding, attention turned to the possible use of the presumably facile elimination 8 of glycosyl selenoxides as a means of accessing these materials.…”