Brønsted Acid Catalyzed Reductive Amination with Benzothiazoline as a Highly Efficient Hydrogen Donor

Abstract

Reductive amination of aldehyde and amine proceeded smoothly in the presence of benzothiazoline as efficient hydrogen source by means of 20 mol% trifluoroacetic acid to give the corresponding amines in excellent yields. Hydrogen-donor abilities of benzothiazoline, benzimidazoline, and benzoxazoline were compared.

reduction - reductive amination - benzothiazoline - transfer hydrogenation - phosphoric acid

References and Notes

For general reviews of metal-catalyzed asymmetric reductive amination, see:

<A NAME="RY03711ST-1A">1a</A> Ohkuma T. Noyori R. In Comprehensive Asymmetric Catalysis   Suppl. 1:  Jacobsen EN. Pfaltz A. Yamamoto H. Springer; New York: 2004. 

<A NAME="RY03711ST-1B">1b</A> Gomez S. Peters JA. Maschmeyer T. Adv. Synth. Catal.  2002,  344:  1037 

<A NAME="RY03711ST-1C">1c</A> Tararov VI. Börner A. Synlett  2005,  203 

For asymmetric synthesis, see:

<A NAME="RY03711ST-2A">2a</A> Blaser H.-U. Buser H.-P. Jalett H.-P. Pugin B. Spindler F. Synlett  1999,  867 

<A NAME="RY03711ST-2B">2b</A> Kadyrov R. Riermeier TH. Angew. Chem. Int. Ed.  2003,  42:  5472 

<A NAME="RY03711ST-2C">2c</A> Li C. Villa-Marcos B. Xiao J. J. Am. Chem. Soc.  2009,  131:  6967 

<A NAME="RY03711ST-2D">2d</A> Steinhuebel D. Sun Y. Matsumura K. Sayo N. Saito T. J. Am. Chem. Soc.  2009,  131:  11316 

<A NAME="RY03711ST-2E">2e</A> Steinhuebel D. Sun Y. Matsumura K. Sayo N. Saito T. J. Am. Chem. Soc.  2009,  131:  11316 

For biocatalysis, see:

<A NAME="RY03711ST-2F">2f</A> Koszelewski D. Lavandera I. Clay D. Guebitz GM. Rozzell D. Kroutil W. Angew. Chem. Int. Ed.  2008,  47:  9337 

For achiral reactions, see:

<A NAME="RY03711ST-3A">3a</A> Chandrasekhar S. Reddy CR. Ahmed M. Synlett  2000,  1655 

<A NAME="RY03711ST-3B">3b</A> Apodaca R. Xiao W. Org. Lett.  2001,  3:  1745 

<A NAME="RY03711ST-3C">3c</A> Gross T. Seayad AM. Ahmad M. Beller M. Org. Lett.  2002,  4:  2055 

<A NAME="RY03711ST-4">4</A> Eisner U. Kuthan J. Chem. Rev.  1972,  72:  1 

For representative reviews on Hantzsch esters, see:

<A NAME="RY03711ST-5A">5a</A> Ouellet SG. Walji AM. MacMillan DWC. Acc. Chem. Res.  2007,  40:  1327 

<A NAME="RY03711ST-5B">5b</A> You S.-L. Chem. Asian J.  2007,  2:  820 

<A NAME="RY03711ST-5C">5c</A> Connon SJ. Org. Biomol. Chem.  2007,  5:  3407 

<A NAME="RY03711ST-5D">5d</A> Rueping M. Sugiono E. Schoepke FR. Synlett  2010,  852 

<A NAME="RY03711ST-6A">6a</A> Steevens JB. Pandit UK. Tetrahedron  1983,  39:  1395 

<A NAME="RY03711ST-6B">6b</A> Fujii M. Aida T. Yoshihara M. Ohno A. Bull. Chem. Soc. Jpn.  1989,  62:  3845 

<A NAME="RY03711ST-6C">6c</A> Itoh T. Nagata K. Kurihara A. Miyazaki M. Ohsawa A. Tetrahedron Lett.  2002,  43:  3105 

See also:

<A NAME="RY03711ST-6D">6d</A> Che J. Lam Y. Synlett  2010,  2415 

<A NAME="RY03711ST-7A">7a</A> Menche D. Arikan F. Synlett  2006,  841 

<A NAME="RY03711ST-7B">7b</A> Zhang Z. Schreiner PR. Synlett  2007,  1455 

<A NAME="RY03711ST-7C">7c</A> Rueping M. Azap C. Sugiono E. Theissmann T. Synlett  2005,  2367 

<A NAME="RY03711ST-7D">7d</A> Wakchaure VN. Nicoletti M. Ratjen L. List B. Synlett  2010,  2708 

See also:

<A NAME="RY03711ST-7E">7e</A> Menche D. Hassfeld J. Li J. Menche G. Ritter A. Rudolph S. Org. Lett.  2006,  8:  741 

<A NAME="RY03711ST-8A">8a</A> Storer RI. Carrera DE. Ni Y. MacMillan DWC. J. Am. Chem. Soc.  2006,  128:  84 

<A NAME="RY03711ST-8B">8b</A> Hoffmann S. Nicoletti M. List B. J. Am Chem. Soc.  2006,  128:  13074 

<A NAME="RY03711ST-8C">8c</A> Wakchaure VN. Zhou J. Hoffmann S. List B. Angew. Chem. Int. Ed.  2010,  49:  4612 

For reviews on chiral Brønsted acid catalysis, see:

<A NAME="RY03711ST-9A">9a</A> Akiyama T. Itoh J. Fuchibe K. Adv. Synth. Catal.  2006,  348:  999 

<A NAME="RY03711ST-9B">9b</A> Akiyama T. Chem. Rev.  2007,  107:  5744 

<A NAME="RY03711ST-9C">9c</A> Connon SJ. Angew. Chem. Int. Ed.  2006,  45:  3909 

<A NAME="RY03711ST-9D">9d</A> Terada M. Chem. Commun.  2008,  4097 

<A NAME="RY03711ST-9E">9e</A> Terada M. Synthesis  2010,  1929 

<A NAME="RY03711ST-9F">9f</A> Zamfir A. Schenker S. Freund M. Tsogoeva SB. Org. Biomol. Chem.  2010,  8:  5262 

For reduction of imines, see:

<A NAME="RY03711ST-10A">10a</A> Hoffmann S. Seayad AM. List B. Angew. Chem. Int. Ed.  2005,  44:  7424 

<A NAME="RY03711ST-10B">10b</A> Rueping M. Sugiono E. Azap C. Theissmann T. Bolte M. Org. Lett.  2005,  7:  3781 

<A NAME="RY03711ST-10C">10c</A> Li GL. Liang YX. Antilla JC. J. Am. Chem. Soc.  2007,  129:  5830 

<A NAME="RY03711ST-10D">10d</A> Kang Q. Zhao ZA. You SL. Adv. Synth. Catal.  2007,  349:  1657 ; Corrigendum: Adv. Synth. Catal. 2007, 349, 2075

<A NAME="RY03711ST-10E">10e</A> Kang Q. Zhao ZA. You SL. Org. Lett.  2008,  10:  2031 

<A NAME="RY03711ST-10F">10f</A> Rueping M. Antonchick AP. Theissmann T. Angew. Chem. Int. Ed.  2006,  45:  3683 

<A NAME="RY03711ST-10G">10g</A> Rueping M. Antonchick AP. Theissmann T. Angew. Chem. Int. Ed.  2006,  45:  6751 

<A NAME="RY03711ST-10H">10h</A> Rueping M. Merino E. Koenigs RM. Adv. Synth. Catal.  2010,  352:  2629 

See also:

<A NAME="RY03711ST-10I">10i</A> Li G. Antilla JC. Org. Lett.  2009,  11:  1075 

<A NAME="RY03711ST-10J">10j</A> Han Z.-Y. Xiao H. Chen X.-H. Gong L.-Z. J. Am. Chem. Soc.  2009,  131:  9182 

<A NAME="RY03711ST-10K">10k</A> Liu X.-Y. Che C.-M. Org. Lett.  2009,  11:  4204 

For reduction by menas of iminium catalysis, see:

<A NAME="RY03711ST-11A">11a</A> Ouellet SG. Tuttle JB. MacMillan DWC. J. Am. Chem. Soc.  2005,  127:  32 

<A NAME="RY03711ST-11B">11b</A> Tuttle JB. Ouellet SG. MacMillan DWC. J. Am. Chem. Soc.  2006,  128:  12662 

<A NAME="RY03711ST-12">12</A> For the study on the hydride donor ability, see: Richter D. Mayr H. Angew. Chem. Int. Ed.  2009,  48:  1958 

<A NAME="RY03711ST-13">13</A> Davies PR, and Askew HF. inventors; US  4708810. 

<A NAME="RY03711ST-14A">14a</A> Chikashita H. Miyazaki M. Itoh K. Synthesis  1984,  308 

<A NAME="RY03711ST-14B">14b</A> Chikashita H. Miyazaki M. Itoh K. J. Chem. Soc., Perkin Trans. 1  1987,  699 

For chiral Brønsted acid catalyzed enantioselective transfer hydrogenation of imines employing benzothiazoline as a hydrogen donor, see:

<A NAME="RY03711ST-15A">15a</A> Zhu C. Akiyama T. Org. Lett.  2009,  11:  4180 

<A NAME="RY03711ST-15B">15b</A> Zhu C. Akiyama T. Adv. Synth. Catal.  2010,  352:  1846 

See also:

<A NAME="RY03711ST-15C">15c</A> Enders D. Liebich JX. Raabe G. Chem. Eur. J.  2010,  16:  9763 

<A NAME="RY03711ST-16">16</A>

Aliphatic amines such as benzylamine and n-pentylamine did not give the reduction products.

<A NAME="RY03711ST-17">17</A>

The reactions were performed with 20 mol% TFA in CH₂Cl₂ at 0.07 M concentration.