Synthetic utility of o-carborane: Novel protective group for aldehydes and ketones

Journal of Organometallic Chemistry

Volumn 574, Issue 1, 1999, Pages 107-115

  Nakamura, Hiroyuki ^a   Aoyagi, Kouichi ^a   Yamamoto, Yoshinori ^a  

^a TOHOKU UNIVERSITY   (Japan)

Author keywords

Carbonyl compounds; O Carborane; Protective group

Indexed keywords

EID: 0000638726     PISSN: 0022328X     EISSN: None     Source Type: Journal    
DOI: 10.1016/S0022-328X(98)00922-X     Document Type: Article

References (21)

1. T.W. Greene, P.G.M. Wuts, Protective Groups in Organic Synthesis, John Wiley, New York, 1991, pp. l75-223.
2. Cyanohydrins are also used as protective groups for aldehydes and ketones because of their stability under Lewis acid conditions. However, they are generally reactive to carbanions and hydride ions such as RLi, Grignard reagents, NaH, LAH, etc. (a) G. Stork, L. Maldonado, J. Am. Chem. Soc. 93 (1971) 5286. (b) D.A. Evans, J.M. Hoffman, L.K. Truesdale, J. Am. Chem. Soc. 95 (1973) 5822. (c) T. Hiyama, H. Oishi, H. Saimoto, Tetrahedron Lett. 26 (1985) 2459. Also see Ref. [1].
3. Cyanohydrins are also used as protective groups for aldehydes and ketones because of their stability under Lewis acid conditions. However, they are generally reactive to carbanions and hydride ions such as RLi, Grignard reagents, NaH, LAH, etc. (a) G. Stork, L. Maldonado, J. Am. Chem. Soc. 93 (1971) 5286. (b) D.A. Evans, J.M. Hoffman, L.K. Truesdale, J. Am. Chem. Soc. 95 (1973) 5822. (c) T. Hiyama, H. Oishi, H. Saimoto, Tetrahedron Lett. 26 (1985) 2459. Also see Ref. [1].
4. Cyanohydrins are also used as protective groups for aldehydes and ketones because of their stability under Lewis acid conditions. However, they are generally reactive to carbanions and hydride ions such as RLi, Grignard reagents, NaH, LAH, etc. (a) G. Stork, L. Maldonado, J. Am. Chem. Soc. 93 (1971) 5286. (b) D.A. Evans, J.M. Hoffman, L.K. Truesdale, J. Am. Chem. Soc. 95 (1973) 5822. (c) T. Hiyama, H. Oishi, H. Saimoto, Tetrahedron Lett. 26 (1985) 2459. Also see Ref. [1].
5. On the other hand, the latter property can become an advantage of the protecting group. Very high asymmetric induction is accomplished by the Lewis acid mediated reactions of chiral acetals. (a) T. Mukaiyama, Angew. Chem., Int. Ed. Engl. 16 (1977) 817. (b) W.S. Johnson, R. Elliott, D. Elliott, J. Am. Chem. Soc. 105 (1983) 2904. (c) W.S. Johnson, C. Edington, J.D. Elliott, I.R. Silverman, J. Am. Chem. Soc. 106 (1984) 7588. (d) Y. Yamamoto, S. Nishii, J. Yamada, J. Am. Chem. Soc. 108 (1986) 7116. Also, see the recent review; S.L. Schreiber, Comprehensive Organic Synthesis, Pergamon Press, Oxford, vol. 1, 1991, pp. 325-354.
6. On the other hand, the latter property can become an advantage of the protecting group. Very high asymmetric induction is accomplished by the Lewis acid mediated reactions of chiral acetals. (a) T. Mukaiyama, Angew. Chem., Int. Ed. Engl. 16 (1977) 817. (b) W.S. Johnson, R. Elliott, D. Elliott, J. Am. Chem. Soc. 105 (1983) 2904. (c) W.S. Johnson, C. Edington, J.D. Elliott, I.R. Silverman, J. Am. Chem. Soc. 106 (1984) 7588. (d) Y. Yamamoto, S. Nishii, J. Yamada, J. Am. Chem. Soc. 108 (1986) 7116. Also, see the recent review; S.L. Schreiber, Comprehensive Organic Synthesis, Pergamon Press, Oxford, vol. 1, 1991, pp. 325-354.
7. On the other hand, the latter property can become an advantage of the protecting group. Very high asymmetric induction is accomplished by the Lewis acid mediated reactions of chiral acetals. (a) T. Mukaiyama, Angew. Chem., Int. Ed. Engl. 16 (1977) 817. (b) W.S. Johnson, R. Elliott, D. Elliott, J. Am. Chem. Soc. 105 (1983) 2904. (c) W.S. Johnson, C. Edington, J.D. Elliott, I.R. Silverman, J. Am. Chem. Soc. 106 (1984) 7588. (d) Y. Yamamoto, S. Nishii, J. Yamada, J. Am. Chem. Soc. 108 (1986) 7116. Also, see the recent review; S.L. Schreiber, Comprehensive Organic Synthesis, Pergamon Press, Oxford, vol. 1, 1991, pp. 325-354.
8. On the other hand, the latter property can become an advantage of the protecting group. Very high asymmetric induction is accomplished by the Lewis acid mediated reactions of chiral acetals. (a) T. Mukaiyama, Angew. Chem., Int. Ed. Engl. 16 (1977) 817. (b) W.S. Johnson, R. Elliott, D. Elliott, J. Am. Chem. Soc. 105 (1983) 2904. (c) W.S. Johnson, C. Edington, J.D. Elliott, I.R. Silverman, J. Am. Chem. Soc. 106 (1984) 7588. (d) Y. Yamamoto, S. Nishii, J. Yamada, J. Am. Chem. Soc. 108 (1986) 7116. Also, see the recent review; S.L. Schreiber, Comprehensive Organic Synthesis, Pergamon Press, Oxford, vol. 1, 1991, pp. 325-354.
9. On the other hand, the latter property can become an advantage of the protecting group. Very high asymmetric induction is accomplished by the Lewis acid mediated reactions of chiral acetals. (a) T. Mukaiyama, Angew. Chem., Int. Ed. Engl. 16 (1977) 817. (b) W.S. Johnson, R. Elliott, D. Elliott, J. Am. Chem. Soc. 105 (1983) 2904. (c) W.S. Johnson, C. Edington, J.D. Elliott, I.R. Silverman, J. Am. Chem. Soc. 106 (1984) 7588. (d) Y. Yamamoto, S. Nishii, J. Yamada, J. Am. Chem. Soc. 108 (1986) 7116. Also, see the recent review; S.L. Schreiber, Comprehensive Organic Synthesis, Pergamon Press, Oxford, vol. 1, 1991, pp. 325-354.
10. TMS-cyanohydrins are readily cleaved under aqueous acidic and basic conditions and under Lewis acid conditions. Others are generally stable to acidic conditions.
11. It was reported that generation of monolithiocarborane 2 by treating o-carborane with n-BuLi was accompanied by dilithiocarborane formation due to the disproportionation reaction of 2 (see F.A. Gome, S.E. Johnson, M.F. Hawthorne, J. Am. Chem. Soc. 113 (1991) 5915). However, we have found that the redistribution reaction can be avoided by carrying out the lithiation of o-carborane under controlled conditions and 2 is then generated in essentially quantitative yield from o-carborane. Also, see Ref. [8].
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