Diastereoselective In and Zn-mediated allylation of pyrazol-4-yl derived (R)-tert-butanesulfinyl imines: synthesis of enantiomerically pure 6-(pyrazol-4-yl)-piperidin-2,4-diones

Amine adducts of triallylborane as highly reactive allylborating agents for Cu(I)-catalyzed allylation of chiral sulfinylimines

The implementation of selective catalytic processes with highly active reagents is an attractive strategy that meets the modern principles of sustainable development of chemistry. In the current study, we for the first time describe the method and general principles of Cu(I)-catalyzed allylation of imines with amine adducts of allylic triorganoboranes. Triallylborane is an extremely reactive compound and cannot be used for the catalytic allylation of imines, whereas its amine adducts are ideal substrates for catalysis. The structure of the amine fragment successfully balances the safety, selectivity and stability of the allylboron reagent, allowing it to demonstrate high activity in catalytic allylation reactions, exceeding many times any known allylboranes. The obtained results are supported by quantitative kinetics data and DFT calculations. The catalytic efficacy of the system was demonstrated on model sulfinylimines (23 examples). High diastereoselectivity up to >99% was achieved, including for the gram-scale synthesis of 2-hydroxyphenyl-derivatives. Taking into account the high reactivity and unsurpassed atom-economy of amine adducts of triallylborane (AAT), they can be considered as prospective allylation reagents with Cu(I) and other appropriate metallocatalysts.

1,2-Additions on Chiral N-Sulfinylketimines: An Easy Access to Chiral α-Tertiary Amines

Chiral α-tertiary amines, a motif present in α,α-disubstituted α-amino acids, in a wide range of natural products, and many drugs and drug candidates, are important targets in organic chemistry. Among the possible strategies, 1,2-addition to chiral N-sulfinyl­ketimines is one of the best routes to form chiral α-tertiary amines with a high level of stereoselectivity. In this review, we focus first on the addition of organometallic reagents or other nucleophiles as enols or ylides to chiral N-sulfinylketimines. Then secondly we cover a selection of applications of these additions in the synthesis of valuable biologically active compounds.

1 Introduction

2 1,2-Addition Reaction Methodologies

2.1 Organolithium Reagent Additions

2.2 Grignard Additions

2.3 Organozinc Reagent Additions

2.4 Organoindium Reagent Additions

2.5 Organoboron Reagent Additions

2.6 Strecker Reactions

2.7 Palladium-Catalyzed Reactions

2.8 Enols, Enolates, and Other Deprotonated Reagent Additions

2.9 Ylide Additions

2.10 Heteroatom Nucleophiles

2.11 Miscellaneous Reactions

3 Applications to the Synthesis of Biologically Active Molecules

4 Conclusions

Dichotomous Selectivity in Indium-Mediated Aza-Barbier-Type Allylation of 2-N-Acetyl Glycosyl Sulfinylimines in Brine: Convenient Access to Potent Anti-Influenza Agents

A highly diastereoselective indium-mediated allylation of 2-N-acetyl glycosyl sulfinylimines in brine under mild reaction conditions is reported. The method allows the achievement of a highly remarkable dichotomous selectivity for substrates, providing a single diastereoisomer of the product in 80-98% yield. With chiral (S)-homoallylic sulfinamide (R_S)-5 and (R_S)-8 formed as key intermediates, two potent anti-influenza agents, zanamivir and zanaphosphor, were synthesized in 50% and 41% overall yields, respectively.

Construction of piperidine-2,4-dione-type azaheterocycles and their application in modern drug development and natural product synthesis

The review surveys the existing routes to piperidine-2,4-dione-type heterocycles including derivatives with the most vital types of biological activity. This heterocyclic platform is ideal for the construction of modern drugs and natural products.

Stereoselective synthesis of novel adamantane derivatives with high potency against rimantadine-resistant influenza A virus strains

A series of (R)- and (S)-isomers of new adamantane-substituted heterocycles (1,3-oxazinan-2-one, piperidine-2,4-dione, piperidine-2-one and piperidine) with potent activity against rimantadine-resistant strains of influenza A virus were synthesized through the transformation of adamantyl-substituted N-Boc-homoallylamines 8 into piperidine-2,4-diones 11 through the cyclic bromourethanes 9 and key intermediate enol esters 10. Biological assays of the prepared compounds were performed on the rimantadine-resistant S31N mutated strains of influenza A - A/California/7/2009(H1N1)pdm09 and modern pandemic strain A/IIV-Orenburg/29-L/2016(H1N1)pdm09. The most potent compounds were both enantiomers of the enol ester 10 displaying IC₅₀ = 7.7 μM with the 2016 Orenburg strain.

New enolate-carbodiimide rearrangement in the concise synthesis of 6-amino-2,3-dihydro-4-pyridinones from homoallylamines

Three-step synthesis of 6-amino-2,3-dihydro-4-pyridinones from homoallylamines involving NBS-mediated cyclization of N-(3-butenyl)ureas to 6-(bromomethyl)-2-iminourethanes, dehydrohalogenation and a novel rearrangement as a key step has been developed. The scope and limitations of the method, as well as the mechanism of the rearrangement, supported by kinetic studies and the isolation of N-(1-adamantyl)carbodiimide, are discussed. The final products, imino-analogues of well known piperidine-2,4-diones, are promising building blocks in the synthesis of bio-/pharmacological compounds.

α-Trifluoromethylated tertiary homoallylic amines: diastereoselective synthesis and conversion into β-aminoesters, γ- and δ-aminoalcohols, azetidines and pyrrolidines

The diastereoselective addition of allyl zinc and allylindium derivatives to α-trifluoromethyl N-tert-butanesulfinyl hemiaminals, bench stable precursors of aryl and alkyl trifluoromethyl ketimines, allows the synthesis of homoallylic amines containing a tetrasubstituted carbon stereocentre bearing a trifluoromethyl group with good diastereoselectivities (up to dr > 99 : 1). This approach was also suitable for accessing chiral homoallylic amines bearing two contiguous stereocenters. The synthetic usefulness of N-tert-butanesulfinyl homoallylamines was illustrated by preparing various trifluoromethylated nitrogen containing bifunctional synthons (aminoesters, aminoalcohols) and small azaheterocycles (azetidines, pyrrolidines).