Hydrogen auto-transfer explained

Hydrogen auto-transfer, also known as borrowing hydrogen, is the activation of a chemical reaction by temporary transfer of two hydrogen atoms from the reactant to a catalyst and return of those hydrogen atoms back to a reaction intermediate to form the final product.[1] [2] [3] [4] Two major classes of borrowing hydrogen reactions exist: (a) those that result in hydroxyl substitution, and (b) those that result in carbonyl addition. In the former case, alcohol dehydrogenation generates a transient carbonyl compound that is subject to condensation followed by the return of hydrogen. In the latter case, alcohol dehydrogenation is followed by reductive generation of a nucleophile, which triggers carbonyl addition. As borrowing hydrogen processes avoid manipulations otherwise required for discrete alcohol oxidation and the use of stoichiometric organometallic reagents, they typically display high levels of atom-economy and, hence, are viewed as examples of Green chemistry.

History

The Guerbet reaction, reported in 1899,[5] is an early example of a hydrogen auto-transfer process. The Guerbet reaction converts primary alcohols to β-alkylated dimers via alcohol dehydrogenation followed by aldol condensation and reduction of the resulting enones. Application of the Guerbet reaction to the development of ethanol-to-butanol processes has garnered interest as a method for the production of renewable fuels.[6] In 1932 using heterogeneous nickel-catalysts Adkins reported the first alcohol aminations that occur through alcohol dehydrogenation-reductive amination.[7] Homogenous catalysts for alcohol amination based on rhodium and ruthenium were developed by Grigg[8] and Watanabe[9] in 1981. The first hydrogen auto-transfer processes that convert primary alcohols to products of carbonyl addition were reported by Michael J. Krische in 2007-2008 using homogenous iridium and ruthenium catalysts.[10] [11] [12]

Hydroxyl substitution

Alcohol aminations are among the most commonly utilized borrowing hydrogen processes.[13] [14] [15] In reactions of this type, alcohol dehydrogenation is followed by reductive amination of the resulting carbonyl compound. This represents an alternative to two-step processes involving conversion of the alcohol to a halide or sulfonate ester followed by nucleophilic substitution

As shown below, alcohol amination has been used on kilogram scale by Pfizer for the synthesis of advanced pharmaceutical intermediates.[16] Additionally, AstraZeneca has used methanol as an alternative to conventional genotoxic methylating agents such as methyl iodide or dimethyl sulfate.[17] Nitroaromatics can also participate as amine precursors in borrowing hydrogen-type alcohol aminations.[18] The formation of carbon–carbon bonds have been achieved through borrowing hydrogen-type indirect Wittig,[19] aldol,[20] Knoevenagel condensations [21] and also through various carbon nucleophiles.[22] [23] Related to the Guerbet reaction, Donohoe and coworkers have developed enantioselective borrowing hydrogen-type enolate alkylations.[24]

Carbonyl addition

As exemplified by the Krische allylation, dehydrogenation of alcohol reactants can be balanced by reduction of allenes, dienes or allyl acetate to generate allylmetal-carbonyl pairs that combine to give products of carbonyl addition. In this way, lower alcohols are directly transformed to higher alcohols in a manner that significantly decreases waste.[25] In 2008, borrowing hydrogen reactions of 1,3-enynes with alcohols to form products of carbonyl propargylation was discovered.[26] An enantioselective variant of this method was recently used in the total synthesis of leiodermatolide A.[27]

Notes and References

  1. Hamid MH, Slatford PA, Williams JM . 2007. Borrowing Hydrogen in the Activation of Alcohols . Advanced Synthesis & Catalysis. en. 349. 10. 1555–1575. 10.1002/adsc.200600638 .
  2. Guillena G, Ramón DJ, Yus M . Alcohols as electrophiles in C--C bond-forming reactions: the hydrogen autotransfer process . Angewandte Chemie . 46 . 14 . 2358–64 . 2007-03-26 . 17465397 . 10.1002/anie.200603794 .
  3. Ketcham JM, Shin I, Montgomery TP, Krische MJ . Catalytic enantioselective C-H functionalization of alcohols by redox-triggered carbonyl addition: borrowing hydrogen, returning carbon . Angewandte Chemie . 53 . 35 . 9142–50 . August 2014 . 25056771 . 4150357 . 10.1002/anie.201403873 .
  4. Nguyen KD, Park BY, Luong T, Sato H, Garza VJ, Krische MJ . Metal-catalyzed reductive coupling of olefin-derived nucleophiles: Reinventing carbonyl addition . Science . 354 . 6310 . aah5133 . October 2016 . 27846504 . 5130112 . 10.1126/science.aah5133 .
  5. Guerbet M . Action de l'Alcool Amylique de Fermentation sur Son Dérivé Sodé. . Action of Amyl Alcohol Fermentation on Its Soda Derivative . French . Comptes rendus de l'Académie des Sciences . Paris . 1899 . 128 . 1002–1004 .
  6. Aitchison H, Wingad RL, Wass DF . 2016-10-07. Homogeneous Ethanol to Butanol Catalysis—Guerbet Renewed . ACS Catalysis. 6. 10. 7125–7132. 10.1021/acscatal.6b01883. 53363379 .
  7. Winans CF, Adkins H . 1932-01-01. The alkylation of amines as catalyzed by nickel. . Journal of the American Chemical Society. 54. 1. 306–312. 10.1021/ja01340a046. 0002-7863.
  8. Grigg R, Mitchell TR, Sutthivaiyakit S, Tongpenyai N . 1981-01-01. Transition metal-catalysed N-alkylation of amines by alcohols . Journal of the Chemical Society, Chemical Communications. en. 12. 611–612. 10.1039/C39810000611. 0022-4936.
  9. 1981-01-01. The ruthenium catalyzed N-alkylation and N-heterocyclization of aniline using alcohols and aldehydes . Tetrahedron Letters. en. 22. 28. 2667–2670. 10.1016/S0040-4039(01)92965-X. 0040-4039. Watanabe . Yoshihisa . Tsuji . Yasushi . Ohsugi . Yukihiro .
  10. Bower JF, Skucas E, Patman RL, Krische MJ . Catalytic C-C coupling via transfer hydrogenation: reverse prenylation, crotylation, and allylation from the alcohol or aldehyde oxidation level . Journal of the American Chemical Society . 129 . 49 . 15134–5 . December 2007 . 18020342 . 10.1021/ja077389b .
  11. Shibahara F, Bower JF, Krische MJ . Ruthenium-catalyzed C-C bond forming transfer hydrogenation: carbonyl allylation from the alcohol or aldehyde oxidation level employing acyclic 1,3-dienes as surrogates to preformed allyl metal reagents . Journal of the American Chemical Society . 130 . 20 . 6338–9 . May 2008 . 18444617 . 2842574 . 10.1021/ja801213x .
  12. Kim IS, Ngai MY, Krische MJ . Enantioselective iridium-catalyzed carbonyl allylation from the alcohol or aldehyde oxidation level using allyl acetate as an allyl metal surrogate . Journal of the American Chemical Society . 130 . 20 . 6340–1 . May 2008 . 18444616 . 2858451 . 10.1021/ja802001b .
  13. Hamid MH, Slatford PA, Williams JM . 2011. The Catalytic Amination of Alcohols . ChemCatChem. en. 3. 12. 1853–1864. 10.1002/cctc.201100255. 38816793 . 1867-3899.
  14. Yang Q, Wang Q, Yu Z . Substitution of alcohols by N-nucleophiles via transition metal-catalyzed dehydrogenation . Chemical Society Reviews . 44 . 8 . 2305–29 . April 2015 . 25661436 . 10.1039/C4CS00496E .
  15. Das. Kuhali. Kumar. Amol. Jana. Akash. Maji. Biplab. 2020-03-01. Synthesis and characterization of N,N-chelate manganese complexes and applications in CN coupling reactions. Inorganica Chimica Acta. en. 502. 119358. 10.1016/j.ica.2019.119358. 214558556 . 0020-1693.
  16. Berliner MA, Dubant SP, Makowski T, Ng K, Sitter B, Wager C, Zhang Y . 2011-09-16. Use of an Iridium-Catalyzed Redox-Neutral Alcohol-Amine Coupling on Kilogram Scale for the Synthesis of a GlyT1 Inhibitor . Organic Process Research & Development. 15. 5. 1052–1062. 10.1021/op200174k. 1083-6160.
  17. Leonard J, Blacker AJ, Marsden SP, Jones MF, Mulholland KR, Newton R . 2015-10-16. A Survey of the Borrowing Hydrogen Approach to the Synthesis of some Pharmaceutically Relevant Intermediates . Organic Process Research & Development. 19. 10. 1400–1410. 10.1021/acs.oprd.5b00199. 1083-6160.
  18. Rubio-Marqués P, Leyva-Pérez A, Corma A . A bifunctional palladium/acid solid catalyst performs the direct synthesis of cyclohexylanilines and dicyclohexylamines from nitrobenzenes . Chemical Communications . 49 . 74 . 8160–2 . September 2013 . 23925659 . 10.1039/c3cc44064h . 10251/45848 . free .
  19. Black. Phillip J.. Edwards. Michael G.. Williams. Jonathan M. J.. 2006. Borrowing Hydrogen: Indirect "Wittig" Olefination for the Formation of C–C Bonds from Alcohols. European Journal of Organic Chemistry. en. 2006. 19. 4367–4378. 10.1002/ejoc.200600070. 1099-0690.
  20. Taguchi. Kazuhiko. Nakagawa. Hideto. Hirabayashi. Tomotaka. Sakaguchi. Satoshi. Ishii. Yasutaka. 2004-01-01. An Efficient Direct α-Alkylation of Ketones with Primary Alcohols Catalyzed by [Ir(cod)Cl]2/PPh3/KOH System without Solvent]. Journal of the American Chemical Society. 126. 1. 72–73. 10.1021/ja037552c. 0002-7863.
  21. Pridmore S, Williams JM . December 2008 . C–C bond formation from alcohols and malonate half esters using borrowing hydrogen methodology . Tetrahedron Letters. en. 49. 52. 7413–7415. 10.1016/j.tetlet.2008.10.059.
  22. Blank. Benoît. Kempe. Rhett. 2010-01-27. Catalytic Alkylation of Methyl-N-Heteroaromatics with Alcohols. Journal of the American Chemical Society. 132. 3. 924–925. 10.1021/ja9095413. 20047316 . 0002-7863.
  23. Jana. Akash. Kumar. Amol. Maji. Biplab. 2021. Manganese catalyzed C-alkylation of methyl N -heteroarenes with primary alcohols. Chemical Communications. en. 57. 24. 3026–3029. 10.1039/D1CC00181G. 33624678 . 232037523 . 1359-7345.
  24. Armstrong RJ, Akhtar WM, Young TA, Duarte F, Donohoe TJ . Catalytic Asymmetric Synthesis of Cyclohexanes by Hydrogen Borrowing Annulations . Angewandte Chemie . 58 . 36 . 12558–12562 . September 2019 . 31265208 . 6771629 . 10.1002/anie.201907514 .
  25. Doerksen RS, Meyer CC, Krische MJ . Feedstock Reagents in Metal-Catalyzed Carbonyl Reductive Coupling: Minimizing Preactivation for Efficiency in Target-Oriented Synthesis . Angewandte Chemie . 58 . 40 . 14055–14064 . October 2019 . 31162793 . 6764920 . 10.1002/anie.201905532 .
  26. Patman RL, Williams VM, Bower JF, Krische MJ . Carbonyl propargylation from the alcohol or aldehyde oxidation level employing 1,3-enynes as surrogates to preformed allenylmetal reagents: a ruthenium-catalyzed C-C bond-forming transfer hydrogenation . Angewandte Chemie . 47 . 28 . 5220–3 . 2008 . 18528831 . 2861420 . 10.1002/anie.200801359 .
  27. Siu YM, Roane J, Krische MJ . Total Synthesis of Leiodermatolide A via Transfer Hydrogenative Allylation, Crotylation, and Propargylation: Polyketide Construction beyond Discrete Allyl- or Allenylmetal Reagents . Journal of the American Chemical Society . 143 . 28 . 10590–10595 . July 2021 . 34237219 . 10.1021/jacs.1c06062 . 8529965 .

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