Monoalkyldecaborane(14) Syntheses via Nucleophilic Alkylation and Hydroboration

Abstract

Two regioselective, high-yield routes to nido-6-alkyldecaborane(14)s via one-pot syntheses are reported. Alkyllithium reagents add to salts of nido-B(10)H(13)(-) to form arachno-6-R-B(10)H(13)(2)(-), which may be protonated using HCl/Et(2)O, first to the corresponding arachno-6-R-B(10)H(14)(-) anion and then, with H(2) loss, to nido-6-R-B(10)H(13). Alternately, olefin hydroboration of arachno-6,9-(SMe(2))(2)-B(10)H(12) produces nido-6-R-8-(SMe(2))-B(10)H(11), which may be reduced, using Superhydrid, to nido-6-R-B(10)H(12)(-), and then protonated with HCl/Et(2)O to nido-6-R-B(10)H(13). X-ray diffraction studies of the following intermediates and products are presented: nido-8-(SMe(2))-B(10)H(12), nido-6-Thx-8-(SMe(2))-B(10)H(11), and nido-6-Thx-B(10)H(13).

Reactions of 6,9-Bis(dimethyl sulfide)- decaborane(14), 6,9-[(CH3)2S]2B10H12: Mechanistic Considerations

“…The product composition was determined by comparison of its 11 B NMR spectrum with that of authentic 5-[(CH3)2S]-B10H11. 16 Likewise, the method of Bridges et al 17 was used to prepare 5-[(CH3)2S]-9-(Thx)-2,4-D2B10H9 from 6,9-[(CH3)2S]2-2,4-D2B10H10 by reaction with 2,3-dimethyl-2-butene. The product composition was determined by comparison of its 11 B NMR spectrum with that of authentic 5-[(CH3)2S]-9-(Thx)B10H11.…”

Macropolyhedral boron-containing cluster chemistry. A synthetic approach via the auto-fusion of [6,9-(SMe2)2-arachno-B10H12]

“…In our present work, we were able to get good single-crystal X-ray diffraction data at 150 K. Using anomalous dispersion we were then able to solve and refine the absolute structure with improved molecular dimensions, a selection of which is given in Table 1. Of these dimensions, the shorter distance B(6)-B(7) of 1.654(3) A ˚, noted before, 23 again is worth emphasizing, because it leads to the suggestion that the broad appearance of the two 11 B NMR resonances arising from these two sites derives from a large interboron internuclear coupling constant 1 J( 11 B-11 B) between these two positions. Otherwise, the 11 B spectrum itself has previously been assigned and discussed, and its similarity to that of the [nido-B 10 H 13 ] − anion noted.…”

“…24 The crystallographic determination of compound 2 has previously been reported. 23 In this previous report, however, it was only possible to solve the structure as a racemic twin in space group P2 1 2 1 2 1 . In our present work, we were able to get good single-crystal X-ray diffraction data at 150 K. Using anomalous dispersion we were then able to solve and refine the absolute structure with improved molecular dimensions, a selection of which is given in Table 1.…”

The hydroboration reaction as a key for a straightforward synthesis of new MRI-NCT agents

“…26 Both early and late transition metal catalysts catalyse the hydroboration of olefins affording 6-alkyl (alkenyl) and 6,9-dialkyldecaborane respectively. [27][28][29][30] Very recently a platinum sequential hydroboration of decaborane to obtain poly(6-alkenyldecaborane) has been published. 31 Sneddon et al proposed a new methodology where the formation of the B-C bond was promoted by an ionic liquid in the absence of any metal catalyst; the best results were observed for reactions with bmimX (X = Cl − , BF 4 − ).…”