An organotin hydride-catalyzed, silicon hydride-mediated method for effecting the conjugate reduction of α,β-unsaturated ketones was developed.
D. S. Hays, M. Scholl, G. C.Fu, J. Org. Chem., 1996, 61, 6751-6752.
A chemoselective reduction of the carbonyl functionality via hydrosilylation using low loadings of a copper(I) catalyst bearing an abnormal NHC takes place at ambient temperature in excellent yield within a very short reaction time. The hydrosilylation reaction of α,β-unsaturated carbonyl compounds gives allyl alcohols in good yields. The catalyst can also be used for azide-alkyne cycloadditions.
S. R. Roy, S. C. Sau, S. K. Mandal, J. Org. Chem., 2014, 79, 9150-9160.
The combination of triethylborane with an alkali metal base catalyzes the reduction of amides with silanes to form amines under mild conditions. In addition, a selective transformation of secondary amides to aldimines and primary amides to nitriles can also be achieved.
W. Yao, H. Fang, Q. He, D. Peng, G. Liu, Z. Huang, J. Org. Chem., 2019, 84, 6084-6093.
A well-defined manganese(I) complex with a commercially available bisphosphine ligand catalyzes selective and efficient hydrosilylations of a broad range of esters to alcohols at 100 °C under solvent-free conditions.
R. R. Behera, R. Ghosh, S. Panda, S. Khamari, B. Bagh, Org. Lett., 2020, 22, 3642-3648.
A nickel-catalyzed reduction of secondary and tertiary amides provides amines. The reaction transforms various amide substrates, proceeds in the presence of esters and epimerizable stereocenters, and can be used to achieve the reduction of lactams. Moreover, this methodology provides a simple tactic for accessing medicinally relevant α-deuterated amines.
B. J. Simmons, M. Hoffmann, J. Hwang, M. K. Jackl, N. K. Garg, Org. Lett., 2017, 19, 1910-1913.
In a straightforward process for the N-alkylation of amines, readily available carboxylic acids and silanes as the hydride source enable an effective C-N bond construction under mild conditions and allow obtaining a broad range of alkylated secondary and tertiary amines, including fluoroalkyl-substituted anilines as well as the bioactive compound Cinacalcet HCl.
I. Sorribes, K. Jung, M. Beller, J. Am. Chem. Soc., 2014, 136, 14314-14319.
Dibutyltin dichloride catalyzes a direct reductive amination of aldehydes and ketones in the presence of phenylsilane as a stoichiometric reductant. Suitable amines included anilines and dialkylamines but not monoalkylamines.
R. Apodaca, W. Xiao, Org. Lett., 2001, 3, 1745-1748.
A copper-catalyzed protocol for reductive methylation of amines and imine with formic acid as a C1 source and phenylsilane as a reductant provides the corresponding methylamines in good to excellent yields under mild conditions.
C. Qiao, X.-F. Liu, X. Liu, L.-N. He, Org. Lett., 2017, 19, 1490-1493.
A Cu-catalyzed reductive aminocarbonylation of primary, secondary, and tertiary alkyl iodides using nitroarenes as the nitrogen source provides a diverse range of secondary N-aryl alkylamides. The single copper catalyst synergistically mediates both carbonylation of alkyl iodides and reduction of nitroarenes, to provide acyl iodides and anilines as possible reactive intermediates.
S. Zhao, N. P. Mankad, Org. Lett., 2019, 21, 10106-10110.
A new strategy for the catalytic asymmetric aldol reaction of ketones was developed that relies on a chiral copper(I) complex-catalyzed domino reduction/aldol reaction sequence in the presence of phenylsilane.
J. Deschamp, O. Chuzel, J. Hannedouche, O. Riant, Angew. Chem. Int. Ed., 2006, 45, 1292-1297.
The sequential combination of Ti-catalyzed hydroamination of alkynes followed by the Ti-catalyzed hydrosilylation of the intermediate imines is an efficient one-pot process for the conversion of alkynes and primary amines into secondary amines.
A. Heutling, F. Pohlki, I. Bytschkov, S. Doye, Angew. Chem. Int. Ed., 2005, 44, 2951-2954.
An indium triiodide catalyzed deoxygenative functionalization of N-sulfonyl amides with silyl cyanide or silyl enolates in the presence of hydrosilanes gives α-cyanoamines and β-aminocarboxyl compounds, respectively.
Y. Inamoto, Y. Kaga, Y. Nishimoto, M. Yasuda, A. Baba, Org. Lett., 2013, 15, 3448-3451.
The In(OAc)3-catalyzed reaction of bromo- and iodoalkanes with PhSiH3 in THF at 70 C gave dehalogenated alkanes in good to high yields in the presence of Et3B and air. 2,6-lutidine as additive enabled an efficient reduction of simple and functionalized iodoalkanes in EtOH. GaCl3 was found to be an effective catalyst for the reduction of haloalkanes with poly(methylhydrosiloxane).
K. Miura, M. Tomita, Y. Yamada, A. Hosomi, J. Org. Chem., 2007, 72, 787-792.
B(C6F5)3 catalyzes dehydrogenative couplings of certain amines and hydrosilanes at elevated temperatures. At higher temperature, the dehydrogenation pathway competes with cleavage of the C-N bond and defunctionalization is obtained. This can be turned into a useful methodology for the transition-metal-free reductive deamination of a broad range of amines.
H. Fang, M. Oestreich, Angew. Chem. Int. Ed., 2020, 59, 11394-11398.
A route to trisubstituted olefins through a palladium-catalyzed alkyne insertion with unactivated alkyl iodides followed by a reduction proceeds under mild conditions and tolerates a range of functional groups and substitution patterns. Mechanistic inquiry suggests that the transformation proceeds through a hybrid radical/organometallic pathway.
E. R. Fruchey, B. M. Monks, A. M. Patterson, S. P. Cook, Org. Lett., 2013, 15, 4362-4365.
An iron(III)-promoted hydroalkynylation of unactivated mono-, di-, and trisubstituted alkenes provides structural diversified alkynes via Csp-Csp3 bond formation.
Y. Shen, B. Huang, J. Zheng, C. Lin, Y. Liu, S. Cui, Org. Lett., 2017, 19, 1744-1747.
A highly Marknovikov selectiv conversion of various olefins to azides was achieved using a cobalt catalyst, 3 equiv of TsN3 as nitrogen source and simple silanes (PhSiH3, TMDSO).
J. Waser, H. Nambu, E. M. Carreira, J. Am. Chem. Soc., 2005, 127, 8294-8295.
A convenient protocol for the catalytic dehydration of aromatic and aliphatic amides using silanes in the presence of catalytic amounts of fluoride allows the synthesis of a wide range of aliphatic and aromatic nitriles with high selectivity under mild conditions.
S. Zhou, K. Junge, D. Addis, S. Das, M. Beller, Org. Lett., 2009, 11, 2461-2464.
In a catalytic system for the chlorination of alcohols under Appel conditions, benzotrichloride is used as a cheap and readily available chlorinating agent in combination with trioctylphosphane as the catalyst and phenylsilane as the terminal reductant under solvent-free conditions. In total, 27 different primary, secondary, and tertiary alkyl chlorides were synthesized in good yields.
L. Longwitz, S. Jopp, T. Werner, J. Org. Chem., 2019, 84, 7863-7870.
An organophosphorus-catalyzed reductive C-N coupling of nitromethane with arylboronic acid derivatives provides N-methylanilines. The small ring organophosphorus-based catalyst (1,2,2,3,4,4-hexamethylphosphetane P-oxide) together with phenylsilane as mild terminal reductant mediate the selective installation of the methylamino group.
G. Li, Z. Qin, A. T. Radosevich, J. Am. Chem. Soc., 2020, 142, 16205-16210.
A mild transition-metal- and photosensitizer-free photoredox system based on the combination of NaI and PPh3 enables a highly selective reduction of nitroarenes. This protocol tolerates a broad range of reducible functional groups such as halogen (even I), aldehyde, ketone, carboxyl, and cyano.
Z. Qu, X. Chen, S. Zhong, G.-J. Deng, H. Huang, Org. Lett., 2021, 23, 5349-5353.
A transition-metal-free synthesis of aryl- and heteroarylamines employs a small-ring organophosphorus-based catalyst and a terminal hydrosilane reductant to drive reductive intermolecular coupling of nitroarenes with boronic acids. Applications to the construction of both Csp2-N (from arylboronic acids) and Csp3-N bonds (from alkylboronic acids) are demonstrated; the reaction is stereospecific with respect to Csp3-N bond formation.
T. V. Nykaza, J. C. Cooper, G. Li, N. Mahieu, A. Ramirez, M. R. Luzung, A. T. Radosevich, J. Am. Chem. Soc., 2018, 140, 15200-15205.
A Fe-catalyzed olefin hydroamination with aryldiazo sulfones provides a broad range of alkylarylazo compounds, that are difficult to access. The reaction offers mild reaction conditions.
Y. Zhang, C. Huang, X. Lin, Q. Hu, B. Hu, Y. Zhou, G. Zhu, Org. Lett., 2019, 21, 2261-2264.
1,2,2,3,4,4-hexamethylphosphetane catalyzes a deoxygenative N-N bond-forming Cadogan heterocyclization of o-nitrobenzaldimines and o-nitroazobenzenes with good functional group compatibility in the presence of phenylsilane as terminal reductant.
T. V. Nykaza, T. S. Harrison, A. Ghosh, R. A. Putnik, A. T. Radosevich, J. Am. Chem. Soc., 2017, 139, 6839-6842.
Catalytic amounts of phosphine and triethylamine enable an efficient protocol for the synthesis of highly functionalized furans via intramolecular Wittig reaction. Silyl chloride as the initial promoter activates the phosphine oxide for reduction, while decomposition of Et3N·HCl resulted in regeneration of base, which mediated formation of phosphorus ylide.
C.-J. Lee, T.-H. Chang, J. K. Yu, G. M. Reddy, M.-Y. Hsiao, W. Lin, Org. Lett., 2016, 18, 3758-3761.