Highly stereoselective synthesis of homoallylic amines based on addition of allyltrichlorosilanes to benzoylhydrazones

Regio- and Enantioselective Synthesis of 1,2-Diamines by Formal Hydroamination of Enamines: Scope, Mechanism, and Asymmetric Synthesis of Orthogonally Protected Bis-Piperazines as a Privileged Scaffold

We have previously reported the first formal hydroamination of enamines for the synthesis of chiral 1,2-diamines. Here, we describe: (i) the discovery, optimization, and substrate expansion of this reaction; (ii) a novel and straightforward protocol for the "click-type" synthesis of enamines in quantitative yield utilizing sodium sulfate in a dual role as an ancillary and dehydrating agent without the need for workup or purification; (iii) the application of this methodology to the first enantioselective synthesis of orthogonally protected 1,1'-(1-(4-fluorophenyl)ethane-1,2-diyl) piperazines, a scaffold for rapid lead optimization in drug discovery; (iv) a computational investigation into the mechanism and rationalization of the enantioselectivities of the reaction.

Regio- and Enantioselective Synthesis of 1,2-Diamine Derivatives by Copper-Catalyzed Hydroamination

A highly regio- and enantioselective synthesis of 1,2-diamine derivatives from γ-substituted allylic pivalamides using copper-catalyzed hydroamination is reported. The N-pivaloyl group is essential, in both facilitating the hydrocupration step and suppressing an unproductive β-elimination from the alkylcopper intermediate. This approach enables an efficient construction of chiral differentially protected vicinal diamines under mild conditions with broad functional group tolerance.

One-pot preparation of trifluoromethylated homoallylic N-acylhydrazines or α-methylene-γ-lactams from acylhydrazines, trifluoroacetaldehyde methyl hemiacetal, allyl bromide and tin

Tin promoted one-pot preparation of trifluoromethylated homoallylic N-acylhydrazines or α-methylene-γ-lactams has been developed instead of using toxic stannanes.

[2+2+2] Cycloadditions of siloxy alkynes with 1,2-diazines: from reaction discovery to identification of an antiglycolytic chemotype

Cycloaddition uncovered: The title reaction produces novel polycyclic compounds with high efficiency and excellent diastereoselectivity under mild reaction conditions. A small-molecule library, synthesized using this reaction, yielded a novel chemotype which inhibited glycolytic ATP production by blocking glucose uptake in CHO-K1 cells. DMF=N,N-dimethylformamide, Tf=trifluoromethanesulfonyl, TIPS=triisopropylsilyl.

Bismuth-catalyzed addition of silyl nucleophiles to carbonyl compounds and imines

Bismuth triflate was found to be an efficient catalyst both in the Mannich-type reaction of silyl enolates and in the Sakurai reaction of allyltrimethylsilane with N-alkoxycarbonylamino sulfones. The reactions proceeded smoothly with a low catalyst loading of Bi(OTf)(3)·4H(2)O (0.5-5.0 mol%) to afford the corresponding protected β-amino carbonyl compounds and homoallylic amines in very good yields (up to 96%). The latter compounds could also be obtained via a bismuth-mediated three-component reaction. We have also developed an efficient vinylogous Mukaiyama aldol reaction of 2-(trimethylsilyloxy)furan with various aromatic aldehydes mediated by bismuth triflate in a low catalyst loading (1 mol%). The reaction proceeds rapidly and affords the corresponding 5-[hydroxy(aryl)methyl]furan-2(5H)-ones in high yields with good to very good diastereoselectivities (diastereoisomeric ratios>98:2). Such selectivities, although previously reported with other Lewis acids, could be achieved with a much lower catalyst loading. 5-[Hydroxy(alkyl)methyl]furan-2(5H)-ones derived from ketones could also be obtained with good diastereoselectivities. The vinylogous Mukaiyama aldol reaction has also been extended to 2,2-dimethyl-6-methylene-4-(trimethyl-silyloxy)-1,3-diox-4-ene using 1 mol% of Bi(OTf)(3)·4H(2)O.

Transition metal-catalyzed decarboxylative allylation and benzylation reactions

A review. Transition metal catalyzed decarboxylative allylations, benzylations, and interceptive allylations are reviewed.

A diastereoselective carbocyclisation of allene-hydrazones through the intramolecular allylic transfer reaction

A diastereoselective synthesis of cyclic hydrazines was achieved from a carbocyclisation of allene-hydrazones by the Pd-catalyzed distannylation of an allene moiety, followed by the transmetallation of allylic stannane intermediates with TiCl4.

Synthesis of homoallylic amines via the palladium-catalyzed decarboxylative coupling of amino acid derivatives

Protected homoallylic amines are synthesized by the decarboxylative coupling of alpha-amino acid derivatives. The catalytic C-C bond-forming reaction relies on the bioinspired decarboxylative metalation of alpha-amino acids to produce alpha-amino anion equivalents. The alpha-amino anion equivalents are intercepted by pi-allyl palladium electrophiles to produce substituted homoallylic amines.

A highly efficient and general method for the ring-opening of aziridines with various nucleophiles in DMSO

Ring-opening of aziridines with various nucleophiles (such as amines, thiols, and silylated nucleophiles) in DMSO under mild conditions without any catalyst afforded the corresponding products in good to excellent yields.

[Development of efficient methods for synthesis of nitrogen-containing compounds using carbamates, acylhydrazines, and ammonia]

For the efficient synthesis of divergent nitrogen-containing compounds of pharmaceutical and agricultural importance, the development of efficient, complementary, and new synthetic methodologies is essential. One of the key subjects is how to introduce nitrogen atoms in to organic molecules. This review summaries our recent efforts on this issue, focusing on the use of carbamates, acylhydrazines, and ammonia as nitrogen sources.

Asymmetric synthesis of trans-2,5-disubstituted pyrrolidines from enantiopure homoallylic amines. Synthesis of pyrrolidine (-)-197B

Iodocyclization of sulfinimine-derived enantiopure homoallylic sulfonamides affords trans-2,5-disubstituted 3-iodopyrrolidines and represents valuable methodology for the asymmetric synthesis of this important heterocyclic ring system.

First enantioselective organocatalytic allylation of simple aldimines with allyltrichlorosilane

A new organocatalytic system, novel chiral bisformamide and in situ generated L-proline-derived allylsilane reagent , which converts different aldimines to homoallylic amines in good to high yields (up to 95%) and good enantioselectivities (up to 85% ee) has been described.

The first catalytic Sakurai reaction of N-alkoxycarbonylamino sulfones with allyltrimethylsilane

We report the first catalytic Sakurai reaction of N-alkoxycarbonylamino sulfones with allylsilanes. The allylation reaction of N-alkoxycarbonylamino phenylsulfones with allyltrimethylsilane proceeded smoothly with low catalyst loading of bismuth triflate (2.0 mol%) to afford the corresponding protected homoallylic amines in moderate to very good yields (up to 96%).

Dual Activation in Asymmetric Allylsilane Addition to Chiral N-Acylhydrazones: Method Development, Mechanistic Studies, and Elaboration of Homoallylic Amine Adducts

[reaction: see text] Chiral N-acylhydrazones derived from commercially available 4-benzyl-2-oxazolidinone provide a rigid, conformationally restricted template to impart facial selectivity in additions to C=N bonds. In the presence of indium(III) trifluoromethanesulfonate [In(OTf)3], N-acylhydrazones undergo highly diastereoselective fluoride-initiated additions of allylsilanes (aza-Sakurai reaction). Mechanistic studies including control experiments and comparisons with allyltributylstannane, allylmagnesium bromide, and allylindium species implicate a dual activation mechanism involving addition of an allylfluorosilicate species to a chelate formed from In(OTf)3 and the chiral N-acylhydrazone. The N-N bonds of the adducts are readily cleaved in a two-step protocol to provide synthetically useful homoallylic N-trifluoroacetamides. Further elaboration of the latter compounds through Wacker oxidation and olefin metathesis provides diversely functionalized building blocks and expands the potential applications of this C-C bond construction approach to asymmetric amine synthesis.