An Efficient Synthesis of Carborane Amines via One-Step Reaction of Carborane Triflates with N-Nucleophiles

Abstract

S y n t h e s i s o f C a r b o r a n e A m i n e s f r o m C a r b o r a n e T r i f l a t e s Abstract: 1-Trifluoromethanesulfonylmethyl-o-carborane and cesium 1-trifluoromethanesulfonylmethyl-1-carba-closo-dodecaborate react with amines in refluxing acetonitrile in the presence of NaOAc without a catalyst to give the corresponding amino derivatives. This approach allows for simple synthesis of neutral and anionic carborane amines not readily available via other synthetic routes.

Chemistry of cobalt bis(1,2-dicarbollide) ion; the synthesis of carbon substituted alkylamino derivatives from hydroxyalkyl derivatives via methylsulfonyl or p -toluenesulfonyl esters

“…Nevertheless, a synthesis of corresponding iodides from recently available hydroxyalkyl derivatives and iodic acid led to incomplete conversions and difficulties in separating the respective alkyliodides from parent compounds. Known alternatives replacing alkyl halide compounds in these reactions are p-toluenesulfonyl (tosyl, Ts), methylsulfonyl (mesyl, Ms) and trifluormethyl sulfonyl (triflate) esters [9,37].…”

“…The primary amines with NH 2 functions directly attached to isomeric dicarbaborane cages are available from lithiation of the CH sites and subsequent reactions with N-(u-bromoalkyl)phthalimides followed by a cleavage of the protective group [5e8]. Synthesis of methylene amino NHReCH 2 e1,2-C 2 B 10 H 11 carborane derivatives was reported proceeding via the reaction of a trifluoromethyl sulfonyl ester with sodium amide or with various amines in the presence of sodium acetate [9].…”

Synthesis, Structural Characterization, and Reactivity Studies of 5-CF3SO3-B10H13

“…One of the most common B-substituted carborane derivatives is the B-halocarboranes, and a number of methods have been developed that allow substitution at different boron sites . The triflate group is often used as a pseudohalogen in many types of organic palladium-coupling and nucleophilic substitution reactions, and recent studies of C-substituted triflated carboranes also suggest a similar utility for polyborane cluster derivatization. However, B-triflated ortho -carboranes have not been available for these applications.…”

Inhibitors of CA IX Enzyme Based on Polyhedral Boron Compounds

“…From this point, carborane chemistry offered several possible solutions for the synthesis of primary amines to use as building blocks. Several routes to alkylamines have been described in the literature comprising of the insertion of alkynes with a protected amino function into open‐cage precursors, [42] reactions of lithiated carborane with N‐protected haloalkyl amines [43] such as N ‐(ω‐bromoalkyl)phthalimides, [44] or synthesis proceeding via reactions of triflate esters [40e,45] with sodium amide [46] . It should be noted that carbon substituted amines with an −NH 2 group directly connected to the cage were excluded from consideration (with the exception of 1‐H 3 N−1‐CB 11 H 11 ), since docking studied proposed that a short linker, such as methylene moiety is necessary condition for attaining high affinity towards CA IX.…”

“…Thus, dramatic decreases in the yield of the corresponding alkylamines were observed. In retrospect, it should be pointed out that the most reliable reaction scheme leading to primary alkylamines proceeds via reactions of triflate esters with sodium amide, [46] or better yet with a toluene solution of NH 3 in an ACE ® pressure flask; or for ortho ‐series via reactions of haloalkyls with a trimethylsilyl‐protected amine group [43a] …”