A highly efficient Zn-catalyzed alkylation of ketones and aldimines with Grignard reagents via trialkylzinc(II) ate complexes minimizes problems with the use of only Grignard reagents, which leads to reduction and aldol side products, and the yield of desired alkylation products could be improved.
M. Hatano, S. Suzuki, K. Ishihara, J. Am. Chem. Soc., 2006, 128, 9998-9999.
N-Benzyldiphenylphosphinamides are deprotonated at the NCα position diastereospecifically upon treatment with t-BuLi in diethyl ether at low temperature. Reaction of the anions with various electrophiles and subsequent cleavage of the P-N linkage affords 1,2-amino alcohols and α-, β-, and γ-amino acids.
P. O. Burgos, I. Fernández, M. J. Iglesias, S. García-Granda, F. L. Ortiz, Org. Lett., 2008, 10, 537-540.
A highly efficient three-component coupling reaction between thioformamides and organolithium and Grignard reagents was developed. The generality of the process has been demonstrated by using various combinations of reactants and reagents.
T. Murai, F. Asai, J. Am. Chem. Soc., 2007, 129, 780-781.
Sequential addition reactions of Grignard reagents to thioformamides give tertiary amines in an efficient manner. The addition of different Grignard reagents can be accomplished by using one equivalent of arylmagnesium reagent in the first step followed by alkyl, alkenyl, aryl, or alkynyl reagents to afford the corresponding amines in good to high yields.
T. Murai, K. Ui, Narengerile, J. Org. Chem., 2009, 74, 5703-5706.
A mild, versatile, copper-catalyzed three-component coupling of organoindium reagents with imines and acid chlorides provides α-substituted amides or N-protected amines in a single step with the sole byproduct being indium trichloride.
D. A. Black, B. A. Arndtsen, Org. Lett., 2006, 8, 1991-1993.
A rhodium complex coordinated with the chiral diene Ph-bod* catalyzed the asymmetric addition of dimethylzinc to N-tosylarylimines to give high yields of chiral 1-aryl-1-ethylamines with high enantioselectivity.
T. Nishimura, Y. Yasuhara, T. Hayashi, Org. Lett., 2006, 8, 979-981.
Various N-toluenesulfonylimines were successfully ethylated with diethylzinc in the presence of copper(II) ditriflate and a chiral amidophosphine ligand in toluene to give the corresponding N-toluenesulfonylamides in good yields and high enantioselectivity.
T. Soeta, K. Nagai, H. Fujihara, M. Kuriyama, K. Tomioka, J. Org. Chem., 2003, 59, 9655-9659.
N-formyl-α-(p-tolysulfonyl)benzylamines are readily available starting materials which upon deprotonation eliminate the sulfinate group to give an acyl imine. The acyl imines further react with alkylzinc reagents in the presence of catalytic amounts of chiral [2.2]paracyclophane-based N,O-ligands to alkylated N-(1-phenylpropyl)formamides with excellent yields and enantioselectivities.
S. Dahmen, S. Braese, J. Am. Chem. Soc., 2002, 124, 5940-5941.
The use of ZnCl2, Me3SiCH2MgCl, and LiCl effectively minimizes problematic side reactions in the 1,2-addition of strongly basic alkyl and aryl Grignard reagents to ketones. Aldimines give secondary amines in high yield. The simplicity of this reliable ZnCl2•Me3SiCH2MgCl•LiCl system might be attractive for industrial as well as academic applications.
M. Hatano, O. Ito, S. Suzuki, K. Ishihara, J. Org. Chem., 2010, 75, 5008-5016.
LnCl3•2 LiCl (Ln = La, Ce, Nd) are superior promoter for the addition of various organometallic reagents to ketones. They also catalyze efficiently the addition of organomagnesium compounds to imines.
A. Krasovskiy, F. Kopp, P. Knochel, Angew. Chem. Int. Ed., 2006, 45, 497-500.
Under selected conditions, the Zr-catalyzed reaction of EtMgCl with imines produces C,N-dimagnesiated compounds, which can be further trapped with electrophiles. The overall transformation provides a new route to bifunctional or cyclic nitrogen-containing compounds such as 1-azaspirocyclic γ-lactams, pyrrolidines and azetidines.
V. Gandon, P. Bertus, J. Szymoniak, Synthesis, 2002, 1115-1120.
Allylic N-sulfonylamines are synthesized in high yields and with high regioselectivities by reaction of N-sulfonylaziridines with excess dimethylsulfonium methylide.
D. M. Hodgson, M. J. Fleming, S. J. Stanway, Org. Lett., 2005, 7, 3295-3298.
Trialkylalanes undergo addition to imines in the presence of a catalytic amount of dichlorodicyclopentadienylzirconium(IV). The reaction tolerates the presence of various functional groups. A possible reaction pathway is discussed.
C. Denhez, J.-L. Vasse, J. Szymoniak, Synthesis, 2005, 2075-2079.
1-Aryl-substituted primary cyclopropylamines are conveniently prepared from aromatic nitriles and diethylzinc in good yields.
S. Wiedemann, D. Frank, H. Winsel, A. de Meijere, Org. Lett., 2003, 5, 753-755.
The reaction of various aromatic nitriles and conjugated alkenenitriles with 1.1 equiv of Ti(OiPr)4 and 2.2 equiv of EtMgBr followed by addition of a Lewis acid gave 1-arylcyclopropylamines and 1-alkenylcyclopropylamines in good yields.
P. Bertus, J. Szymoniak, J. Org. Chem., 2003, 68, 7133-7136.
The combination of ytterbium trifluoromethanesulfonate [Yb(OTf)3] and chlorotrimethylsilane catalyzed the imino ene reaction of N-tosyl aldimine with α-methylstyrene to give a homoallylamine in excellent yield. The addition of a catalytic amount of silane (TMSCl or TMS(OTf)) increased the yield dramatically.
M. Yamanaka, A. Nishida, M. Nakagawa, Org. Lett., 2000, 2, 159-161.
A nucleophilic trifluoromethylation reaction of carbonyl compounds with Ruppert’s reagent, Me3SiCF3, was efficiently promoted by a P(t-Bu)3-DMF system. Imines were also converted to the desired α-trifluoromethyl amines under similar reaction conditions.
S. Mizuta, N. Shibata, T. Sato, H. Fujimoto, S. Nakamura, T. Toru, Synlett, 2006, 267-270.
Alkoxide-induced nucleophilic pentafluoroethylation and trifluoromethylation of aldehydes, ketones, and imines using pentafluoroethyl phenyl sulfone and trifluoromethyl phenyl sulfone, respectively, have been successfully achieved.
G. K. S. Prakash, Y. Wang, R. Mogi, J. Hu, T. Mathew, G. A. Olah, Org. Lett., 2010, 12, 2932-2935.
β-Functionalized sulfonamides were produced in good yields by the regioselective ring opening of N-tosylaziridines with trimethylsilylated nucleophiles, catalyzed by N,N,N',N'-tetramethylethylenediamine (TMEDA).
S. Minakata, Y. Okada, Y. Oderaotoshi, M. Komatsu, Org. Lett., 2005, 7, 3509-3512.