Titanium(IV)(salen) and Vanadium(V)(salen) Complexes Derived from C ₂- and C ₁-Symmetric Diamines for Asymmetric Cyanohydrin Synthesis

Abstract

Titanium and vanadium salen complexes have been prepared from C₂- and C ₁-symmetric acyclic diamines. All of the complexes catalysed the asymmetric addition of trimethylsilyl cyanide to benzaldehyde and the sense of asymmetric induction was determined by the nature of the substituents. The vanadium complex of a valine-derived diamine gave good results with a range of aromatic and aliphatic aldehydes.

cyanohydrins - homogenous catalysis - asymmetric catalysis - Schiff bases - titanium

References and Notes

For reviews of the development and applications of these catalysts, see:

<A NAME="RD11308ST-1A">1a</A> North M. Tetrahedron: Asymmetry  2003,  14:  147 

<A NAME="RD11308ST-1B">1b</A> Achard TRJ. Clutterbuck LA. North M. Synlett  2005,  1828 

<A NAME="RD11308ST-2A">2a</A> Belokon’ YN. Caveda-Cepas S. Green B. Ikonnikov NS. Khrustalev VN. Larichev VS. Moscalenko MA. North M. Orizu C. Tararov VI. Tasinazzo M. Timofeeva GI. Yashkina LV. J. Am. Chem. Soc.  1999,  121:  3968 

<A NAME="RD11308ST-2B">2b</A> Belokon’ YN. North M. Parsons T. Org. Lett.  2000,  2:  1617 

<A NAME="RD11308ST-2C">2c</A> Belokon’ YN. Green B. Ikonnikov NS. North M. Parsons T. Tararov VI. Tetrahedron  2001,  57:  771 

<A NAME="RD11308ST-2D">2d</A> Belokon’ YN. Maleev VI. North M. Usanov DL. Chem. Commun.  2006,  4614 

<A NAME="RD11308ST-3">3</A> Belokon’ YN. Blacker AJ. Clutterbuck LA. Hogg D. North M. Reeve C. Eur. J. Org. Chem.  2006,  4609; and references therein 

<A NAME="RD11308ST-4A">4a</A> Belokon’ YN. Blacker J. Clutterbuck LA. North M. Org. Lett.  2003,  5:  4505 

<A NAME="RD11308ST-4B">4b</A> Belokon’ YN. Ishibashi E. Nomura H. North M. Chem. Commun.  2006,  1775 

<A NAME="RD11308ST-4C">4c</A> Belokon YN. Clegg W. Harrington RW. Ishibashi E. Nomura H. North M. Tetrahedron  2007,  63:  9724 

<A NAME="RD11308ST-5">5</A> Belokon’ YN. Green B. Ikonnikov NS. North M. Tararov VI. Tetrahedron Lett.  1999,  40:  8147 

<A NAME="RD11308ST-6A">6a</A> Stinson SC. Chem. Eng. News  2001,  79:  35 

<A NAME="RD11308ST-6B">6b</A> Gröger H. Adv. Synth. Catal.  2001,  343:  547 

<A NAME="RD11308ST-6C">6c</A> Blacker AJ. North M. Chem. Ind. (London)  2005,  22 

<A NAME="RD11308ST-7">7</A> Larrow JF. Jacobsen EN. Gao Y. Hong Y. Nie X. Zepp CM. J. Org. Chem.  1994,  59:  1939 

<A NAME="RD11308ST-8A">8a</A> Neumann WL. Rogic MM. Dunn TJ. Tetrahedron Lett.  1991,  32:  5865 

<A NAME="RD11308ST-8B">8b</A> Bambridge K. Begley MJ. Simpkins NS. Tetrahedron Lett.  1994,  35:  3391 

<A NAME="RD11308ST-8C">8c</A> Alvaro G. Grepioni F. Savoia D. J. Org. Chem.  1997,  62:  4180 

<A NAME="RD11308ST-8D">8d</A> Roland S. Mangeney P. Alexakis A. Synthesis  1999,  228 

<A NAME="RD11308ST-9A">9a</A> Pan W. Feng X. Gong L. Hu W. Li Z. Mi A. Jiang Y. Synlett  1996,  337 

<A NAME="RD11308ST-9B">9b</A> Jiang Y. Gong L. Feng X. Hu W. Pan W. Li Z. Mi A. Tetrahedron  1997,  53:  14327 

<A NAME="RD11308ST-10">10</A> Tararov VI. Hibbs DE. Hursthouse MB. Ikonnikov NS. Malik KMA. North M. Orizu C. Belokon’ YN. Chem. Commun.  1998,  387 

<A NAME="RD11308ST-11">11</A>

Benzaldehyde (0.10 mL, 0.98 mmol) and catalyst 5, 6, 8, or 9 (0.1-10 mol%) were dissolved in freshly distilled CH₂Cl₂ (5 mL). Trimethylsilyl cyanide (0.14 mL, 1.08 mmol, 1.1 equiv) was added, and the reaction was stirred at r.t. overnight. The resulting solution was filtered through a pad of SiO₂ using CH₂Cl₂ as eluent. Solvent was removed in vacuo to give mandelonitrile trimethylsilyl ether as a yellow oil. The conversion was determined by ^¹H NMR spectroscopy. The mandelonitrile trimethylsilyl ether and Sc(OTf)₃ (1 mol%) were then dissolved in MeCN (5 mL), and Ac₂O (2.0 equiv) was added. The reaction mixture was stirred at r.t. for 20 min, then filtered through a pad of SiO₂ using CH₂Cl₂ as eluent. Solvent was removed in vacuo to give mandelonitrile acetate as a yellow oil which was analysed by chiral GC to determine its ee.

<A NAME="RD11308ST-12">12</A> Norsikian S. Holmes I. Lagasse F. Kagan HB. Tetrahedron Lett.  2002,  43:  5715 

<A NAME="RD11308ST-13">13</A> For a discussion of the stereochemistry of octahedral metal complexes bearing salen ligands as it applies to asymmetric cyanohydrin synthesis, see: Belokon’ YN. Clegg W. Harrington RW. Young C. North M. Tetrahedron  2007,  63:  5287 

<A NAME="RD11308ST-14A">14a</A> Belokon’ YN. Fuentes J. North M. Steed JW. Tetrahedron  2004,  60:  3191 

<A NAME="RD11308ST-14B">14b</A> Darensbourg DJ. Mackiewicz RM. Rodgers JL. Fang CC. Billodeaux DR. Reibenspies JH. Inorg. Chem.  2004,  43:  6024 

<A NAME="RD11308ST-15A">15a</A> Dey S. Karukurichi KR. Shen W. Berkowitz DB. J. Am. Chem. Soc.  2005,  127:  8610 

<A NAME="RD11308ST-15B">15b</A> Cohen CT. Thomas CM. Peretti KL. Lobkovsky EB. Coates GW. Dalton Trans.  2006,  237 

<A NAME="RD11308ST-15C">15c</A> Malkov AV. Gouriou L. Lloyd-Jones GC. Star I. Langer V. Spoor P. Vinader V. Kočovsk P. Chem. Eur. J.  2006,  12:  6910 

<A NAME="RD11308ST-16">16</A> Kitaura E. Nishida Y. Okawa H. Kida S. J. Chem. Soc., Dalton Trans.  1987,  3055 

<A NAME="RD11308ST-17A">17a</A> Cashin B. Cunningham D. Gallagher JF. McArdle P. Higgins T. J. Chem. Soc., Chem. Commun.  1989,  1445 

<A NAME="RD11308ST-17B">17b</A> Hoshina G. Tsuchimoto M. Ohba S. Acta Crystallogr., Sect. C  1999,  55:  1812 

<A NAME="RD11308ST-17C">17c</A> Choudhary NF. Connelly NG. Hitchcock PB. Leigh GJ. J. Chem. Soc., Dalton Trans.  1999,  4437 

<A NAME="RD11308ST-17D">17d</A> Tsuchimoto M. Hoshina G. Uemura R. Nakajima K. Kojima M. Ohba S. Bull. Chem. Soc. Jpn.  2000,  73:  2317