Benzeneseleninic anhydride dehydrogenation

Subsequent ring closure with ammonia, hydrogenation using PtO2/H2 or Pd-C/H2 [32], DCC/HOBt-mediated amidation with t-butyl amine, followed by dehydrogenation using benzeneseleninic anhydride or 2,3-dichloro-5,6-dicyano-l, 4-benzoquinone (DDQ)/bis(trimethylsilyl)-trifluoroacetamide (BSTFA) [33] combination afforded 4. 

Dehydrogenation of 3-kelo steroids. The dehydrogenation of 3-keto steroids to l,4-diene-3-ones with benzeneseleninic anhydride (8, 31) can be carried out in comparable yield by use of a process in which the benzeneseleninic anhydride is used in catalytic amounts and is continuously regenerated from diphenyl diselenide by oxidation with iodylbenzene. In practice, m-iodylbenzoic acid is a more convenient reagent, since m-iodobenzoic acid is easily recovered. 12-Keto and 12-hydroxy steroids arc oxidized by the catalytic system to A9(1 - -keto steroids in high yield. In fact, methyl desoxycholate (1) can be oxidized in this way directly to the trienedione 2 in 64% yield.1... 

In an interesting extension of the use of benzeneseleninic anhydride. Barton and coworkers ° have dehydrogenated steroidal and other oxazolines e.g. 25) in high yield (equation 13). This type of reaction has considerable potential for a wide variety of heterocyclic systems, due to the acidity of exocyclic... 

Little work appears to have been carried out with benzeneseleninic anhydride on substrates other than steroidal or triterpenoid compounds, but it seems likely that the stronger conditions required to effect oxidation with this reagent makes it less attractive than Ae two-step procedure described above. Indeed, in the few instances repotted it failed to convert hydrocinnamamitte into ciimamamide, and is said to be of no value for the dehydrogenation of acyclic esters. There are, however, several reports in which either catalytic or stoichiometric benzeneseleninic anhydride has effectively dehydrogenated cyclic ketones in high yield, a typical example being illustrated in equation (12). ... 

Benzeneseleninic anhydride, C5HjSe(0)0(0)SeC5Hs, which is prepared in situ from diphenyldiselenide and tert-hniyX hydroperoxide, is used for the oxidation of alcohols to aldehydes or ketones [525]. This reagent is a suitable dehydrogenating agent for the introduction of double bonds a to carbonyl groups [526] and the regeneration of ketones from their oximes, semicarbazones, and phenylhydrazones [527]. 

DEHYDROGENATION Benzeneseleninic anhydride. n-Butyllithium-Tetra-methylethylenediamine. 2,3-Dlchloro-5,6-dicyano-l, 4-benzoquinone. Fenchone. Nickel peroxide. Palladium catalysts. 

Lysergol, ( )-isolysergol, ( )-elymoclavine Dehydrogenation of indolines to indoles with benzeneseleninic anhydride [18]... 

Dehydrogenation of steroidal ketones to give the a,/8-unsaturated species can be accomplished efficiently using benzeneseleninic anhydride.Ketone to enone conversion can also be attained by hydride-ion abstraction from the corresponding trialkylsilyl enol ether [equation (26)]. ... 

Benzeneseleninic acid and anhydride appear to be attractive alternatives to selenium dioxide as dehydrogenation agents of steroidal ketones (31) and amides (32). Potassium fencholate as the base, and fenchone as hydride acceptor, is an effective mixture for deprotonation-elimination of acidic C—H bonds, e.g. (33) to (34) in 90% yield." ... 

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