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ChemComm
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COMMUNICATION
Journal Name
coworkers have reported the isomerization of AB to
diammoniate of diborane (DADB) prior to dehydrogenation in
glyme at 80 oC.11 On this basis, hydroboration via the
intermediacy of DADB is a possibility. However, no DADB was
observed during the course of our experiments. Likewise, the
precursor to DADB, ammonia diborane (AaDB) was also not
observed in the 11B NMR spectrum.27
In summary, a novel, convenient, open-air hydroboration
protocol28 using AB in refluxing THF has been described. This is
the first report of an uncatalyzed hydroboration wherein the
Lewis base (ammonia) is retained in the product. This safe
alternative to traditional hydroboration provides either
trialkylborane-ammonia complexes from terminal alkenes or
aminodialkylboranes from internal alkenes. Oxidation of these
hydroboration products provides the corresponding alcohols in
high yields. The high borane content (45%) and air-stability of
AB are major advantages to this protocol. We believe that the
ability to carry out hydroboration without the need for inert
conditions will have tremendous implications in organic
synthesis, industrial chemistry, and chemical education.
Synthetic applications of aminodialkylboranes are being
currently pursued in our laboratories.
26207. (b) P. V. Ramachandran and A. S. Kulkarni, Inorg.
DOI: 10.1039/C6CC06151F
Chem., 2015, 54, 5618.
11 For details regarding the thermal dehydrogenation of AB in
glyme at 80 oC see: W. J. Shaw, J. C. Linehan, N. K. Szymczak,
D. J. Heldebrant, C. Yonker, D. M. Camaioni, R. T. Baker and
T. Autrey, Angew. Chem., Int. Ed., 2008, 47, 7493.
12 (a) P. V. Ramachandran, H. Mistry, A. S. Kulkarni and P. D.
Gagare, Dalton Trans., 2014, 43, 16580. (b) X. Chen, X. Bao,
B. Billet, S. G. Shore and J.-C. Zhao, Chem. Eur. J., 2012, 18
11994. (c) D. J. Heldebrant, A. Karkamkar, J. C. Linehan and T.
Autrey, Energy Environ. Sci., 2008, , 156. (d) P. V.
,
1
Ramachandran and A. S. Kulkarni, Int. J. Hydrogen Energy,
2016, DOI: 10.1016/j.ijhydene.2016.06.231.
13 Routes to aminodialkylboranes from tetramethyldiborane:
(a) H. I. Schlesinger, L. Horvitz and A. B. Burg J. Am. Chem.
Soc., 1936, 58, 409. (b) P. C. Moews and R. W. Parry, Inorg.
Chem., 1966, 5, 1552.
14 Routes to aminodialkylboranes from dialkylborane
derivatives: (a) H. Nöth and H. Vahrenkamp, J. Organomet.
Chem., 1969, 16, 357. (b) R. B. Booth and C. A. Kraus, J. Am.
Chem. Soc., 1952, 74, 1415. (c) A. J. Ashe III, W. Klein and R.
Rousseau, Organometallics, 1993, 12, 3225. (d) U. Hoebel, H.
Nöth and H. Prigge, Chem. Ber. 1986, 119, 325. (e) L. F.
Hohnstedt, J. P. Brennan and K. A. Reynard, J. Chem. Soc. A
1970, 2455. (f) R. A. Bartlett, H. Chen, H. V. Rasika Dias, M.
M. Olmstead and P. P. Power, J. Am. Chem. Soc., 1988, 110
,
Financial support from the Herbert C. Brown Center for
Borane Research is gratefully acknowledged. We thank Prof. E.
D. Jemmis of IISc Bangalore, India for helpful discussions.
446. (g) G. E. Coates and J. G. Livingstone, J. Chem. Soc. 1961,
4909.
15 Ammonia-triethylborane is reported to decompose on
complete removal of THF. A. N. Marziale, A. Friedrich, I.
Klopsch, M. Drees, V. R. Celinski, J. S. Günne and S.
Schneider, J. Am. Chem. Soc., 2013, 135, 13342.
16 (a) H. Nöth, and B. Wrackmeyer, Nuclear Magnetic
Resonance Spectroscopy of Boron Compounds; Springer-
Verlag: Berlin, 1978; ch. 9, pp. 290. (b) Ref. 16(a), ch. 9, pp.
168. (c) V. Pons, R. T. Baker, N. K. Szymczak, D. J. Heldebrant,
J. C. Linehan, M. H. Matus, D. J. Grant and D. A. Dixon, Chem.
Commun., 2008, 48, 6597.
Notes and references
1
H. C. Brown and B. C. Subba Rao, J. Am. Chem. Soc., 1959, 81
6428.
,
2
(a) H. C. Brown, Organic Syntheses Via Boranes, Wiley, New
York, 1975. (b) H. C. Brown and P. V. Ramachandran, Pure
Appl. Chem. 1991, 63, 307. (c) A. Pelter, K. Smith and H. C.
Brown, Borane Reagents, Academic Press: San Diego, CA,
1988. For other recent hydroboration reagents, see:
17 See ESI for the spectral data of 3a
.
18 H. C. Brown and G. Zweifel, J. Am. Chem. Soc., 1960, 82
,
Di(isopropylprenyl)borane: (c) A. V. Kalinin, S. Scherer and V.
4708.
Snieckus, Angew. Chem., Int. Ed., 2003, 42, 3399. NHC-
borane: (d) Prokofjevs, A.; Boussonniere, A.; Li, L.; Bonin, H.;
Lacote, E.; Curran, D. P.; Vedejs, E. J. Am. Chem. Soc. 2012,
19 For further details on the regioselectivity in hydroboration
see: Y. Oyola and D. A. Singleton, J. Am. Chem. Soc.,
2009, 131, 3130.
134, 12281. (e) Pan, X.; Boussonniere, A.; Curran, D. P. J. Am.
Chem. Soc. 2013, 135, 14433.
20 See ESI for details.
21 0.5 equiv. of AB were utilized with the prior knowledge that
cyclohexene forms selectively the dihydroborated product
with BTHF and BMS.
3
4
J. V. B. Kanth, Aldrichimica Acta, 2002, 35, 57.
R. O. Hutchins, K. Learn, B. Nazer, D. Pytlewski and A. Pelter,
Org. Prep. Proced. Int., 1984, 16, 335.
22 Ammonia-diethylborane complex is known to
dehydrogenate even at room temperature. See ref. 13b
23 (a) H. C. Brown, J. Chandrasekharan, and K. K. Wang, Pure
Appl. Chem., 1983, 55, 1387. (b) H. C. Brown and J.
Chandrasekharan, J. Am. Chem. Soc., 1984, 106, 1863.
24 (a) D. J. Pasto, B. Lepeska and T.-C. Cheng, J. Am. Chem. Soc.,
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Balasubramaniyan, J. Am. Chem. Soc., 1972, 94, 6090.
25 T. Clark, D. Wilhelm and P. V. R. Schleyer, J. Chem. Soc.,
Chem. Commun., 1983, 606.
26 K. N. Houk, X. Wang, Y. Li, Y.-D. Wu, M. N. Paddon-Row and
N. G. Rondan, J. Org. Chem., 1990, 55, 2601.
27 X. Chen, X. Bao, J.-C. Zhao and S. G. Shore, J. Am. Chem. Soc.,
2011, 133, 14172.
5
6
H. C. Brown, K. J. Murray, L. J. Murray, J. A. Snover and G.
Zweifel, J. Am. Chem. Soc., 1960, 82, 4238
.
(a) A. S. Weller, L. J. Sewell and A. B. Chaplin, Dalton Trans.,
2011, 40, 7499. (b) H. C. Johnson, R. Torry-Harris, L. Ortega,
R. Theron, J. S. McIndoe and A. S. Weller, Catal. Sci. Technol.,
2014,
4, 3486.
7
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(a) A. G. Karatjas and E. Vedejs, J. Org. Chem., 2008, 73
,
9508.(b) M. Scheideman, G. Wang and E. Vedejs, J. Am.
Chem. Soc., 2008, 130, 8669.
(a) P. V. Ramachandran and P. D. Gagare, Inorg. Chem., 2007,
46, 7810. (b) P. V. Ramachandran, A. S. Kulkarni, M. A. Pfeil,
J. D. Dennis, J. D. Willits, S. D. Heister, S. F. Son and T. L.
Pourpoint, Chem. Eur. J., 2014, 20, 16869.
For recent reviews on AB see: (a) H. Lia, Q. Yanga, X. Chena
and S. G. Shore, J. Organometal. Chem., 2014, 751, 60. (b) Z.
-G. Huang and T. Autrey, Energy Environ. Sci., 2012, 5, 9257.
9
28 For recent reports on the addition of Bis(pinacolato)diboron
to unsaturated C-C bonds under open-flask conditions, see:
(a) H. Iwamoto, K. Kubota and H. Ito, Chem. Commun., 2016,
52, 5916. (b) Z. Yao, S. Hong, W. Zhang, M. Liu and W. Deng,
Tetrahedron Lett., 2016, 57, 910.
(c) A. Staubitz, A. P. M. Robertson and I. Manners, Chem.
Rev. 2010, 110, 4079.
4 | J. Name., 2012, 00, 1-3
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