Papers by Peter Szolcsanyi
The two-part critical review deals with the metal-catalyzed intramolecular hydroaminations of alk... more The two-part critical review deals with the metal-catalyzed intramolecular hydroaminations of alkenyl amines having terminal double bond. In this first part, the description of the hydroamination as well as the substrate activation via Thorpe-Ingold effect and/or gem-dialkyl/aryl-substitution is presented at the beginning. The main body summarizes the employment of known hydroamination catalysts based on group I and IIA metals, lanthanides and actinides in the direct preparation of saturated aza-heterocycles. The focus is given to the efficiency and stereoselectivity of aminocyclizations. The plausible mechanistic proposals are also presented and analogous ones are compared. The review covers the respective literature published until January 2009.
Molecules
Lilac aldehydes are considered as principal olfactory molecules of lilac flowers. We have designe... more Lilac aldehydes are considered as principal olfactory molecules of lilac flowers. We have designed, prepared, and evaluated a set of racemic seco-analogues of such natural products. The synthesis employs commercially available α-chloroketones as substrates that are transformed in four steps to target compounds. Their qualitative olfactory analysis revealed that the opening of the tetrahydrofuran ring leads to a vanishing of original flowery scent with the emergence of spicy aroma accompanied by green notes, and/or fruity aspects of novel seco-analogues. These results suggest the important osmophoric role of THF moiety for the generation of the typical flowery aroma associated with lilac aldehydes.
Molecules
The advantageous properties of ethylene glycol diacetate (EGDA) qualify it as a useful substitute... more The advantageous properties of ethylene glycol diacetate (EGDA) qualify it as a useful substitute for glycerol triacetate (GTA) for various green applications. We scrutinised the lipase-mediated acetylation of structurally diverse alcohols in neat EGDA furnishing the range of naturally occurring fragrant acetates. We found that such enzymatic system exhibits high reactivity and selectivity towards activated (homo) allylic and non-activated primary/secondary alcohols. This feature was utilised in the scalable multigram synthesis of fragrant (Z)-hex-3-en-1-yl acetate in 70% yield. In addition, the Lipozyme 435/EGDA system was also found to be applicable for the chemo-selective acetylation of (hydroxyalkyl) phenols as well as for the kinetic resolution of chiral secondary alcohols. Lastly, its discrimination power was demonstrated in competitive experiments of equimolar mixtures of two isomeric alcohols. This enabled the practical synthesis of 1-pentyl acetate isolated as a single prod...
Molecules
(S)-5-Methylhept-2-en-4-one is a key flavour compound in hazelnuts. We have performed its chiral-... more (S)-5-Methylhept-2-en-4-one is a key flavour compound in hazelnuts. We have performed its chiral-pool-based chemoenzymatic synthesis with 39% overall yield (73% ee). The four-step aldol-based sequence avoids the use of highly reactive and/or toxic reagents, does not require anhydrous conditions and uses only distillation as the purification method. Thus, such methodology represents a green and scalable alternative to only two stereoselective approaches towards this natural product known so far. In addition, we have designed and prepared a set of new (di)enones as achiral synthetic analogues of the title compound. The results of their sensory analyses clearly show that relatively minor structural changes of the natural molecule significantly alter its olfactory properties. Thus, simple (poly)methylation completely changes the original hazelnut aroma of (S)-5-methylhept-2-en-4-one and shifts the odour of its analogues to eucalyptus, menthol, camphor, and sweet aroma.
SynOpen
The reaction of tosylated 2-alkoxypyrazines with potassium halides led to the unexpected formatio... more The reaction of tosylated 2-alkoxypyrazines with potassium halides led to the unexpected formation of N-alkylated pyrazinones. Such rare example of substitutive C–O → C–N rearrangement on pyrazines was then scrutinised by using various nucleophiles to afford the respective products in moderate to good yields. This method provides a direct access to N-alkylated-1H-pyrazin-2-ones. The formation of the rearranged products is conveniently and reliably determined by characteristic NMR shifts of their heteroaromatic protons.
Synthetic Communications
The unexpected formation of previously nondescribed (semi) conjugated ethyl trienoate revealed it... more The unexpected formation of previously nondescribed (semi) conjugated ethyl trienoate revealed its powerful aroma of fresh pineapple. Thus, we have designed, prepared and evaluated a set of its carbonyl analogues as mixtures of (E/Z)-isomers. Although their synthesis from natural ocimene led to target compounds in low yields, optimized preparation from geranyl acetate furnished an aldehyde as high-yielding common intermediate on multigram scale. A series of its Wittig olefinations provided corresponding (E,E)-configured carbonyl dienes. Final acid-catalyzed elimination of allylic acetates provided the desired "pineapple" target in moderate yield. Sensory analysis revealed that only the parent compound possesses the typical pineapple aroma. Although analogous t Bu-and/or Bn-esters feature an additional green note, the most similar Me-ester differs by its fresh woody aroma analogously to methyl ketone.
Synthesis
This electronic reprint is provided for noncommercial and personal use only: this reprint may be ... more This electronic reprint is provided for noncommercial and personal use only: this reprint may be forwarded to individual colleagues or may be used on the author's homepage. This reprint is not provided for distribution in repositories, including social and scientific networks and platforms.
The two-part critical review deals with the metal-catalyzed intramolecular hydroaminations of alk... more The two-part critical review deals with the metal-catalyzed intramolecular hydroaminations of alkenyl amines having terminal double bond. In this first part, the description of the hydroamination as well as the substrate activation via Thorpe-Ingold effect and/or gem-dialkyl/aryl-substitution is presented at the beginning. The main body summarizes the employment of known hydroamination catalysts based on group I and IIA metals, lanthanides and actinides in the direct preparation of saturated aza-heterocycles. The focus is given to the efficiency and stereoselectivity of aminocyclizations. The plausible mechanistic proposals are also presented and analogous ones are compared. The review covers the respective literature published until January 2009.
The two-part critical review deals with the metal-catalyzed intramolecular hydroaminations of alk... more The two-part critical review deals with the metal-catalyzed intramolecular hydroaminations of alkenyl amines having terminal double bond. Following the first part, this second one summarizes the employment of known hydroamination catalysts based on various transition metals in the direct preparation of pyrrolidines and piperidines. The focus is given to the efficiency and stereoselectivity of respective aminocyclizations. The plausible mechanistic proposals of metal catalysis are presented. The last section highlights the use of Brønsted acids as hydroamination catalysts. The review covers the respective literature published until October 2012.
Acta crystallographica. Section C, Crystal structure communications, Jan 15, 2000
The absolute configuration at the new stereogenic centre during the key step of the total synthes... more The absolute configuration at the new stereogenic centre during the key step of the total synthesis was established byX-ray analysis of the title compound, C(7)H(15)NO(4)(+).Cl(-).
Tetrahedron, 2006
The total synthesis of two novel Lido and L-altro configured 6-chloro-1,5,6-trideoxyiminohexitols... more The total synthesis of two novel Lido and L-altro configured 6-chloro-1,5,6-trideoxyiminohexitols featuring a highly diastereoselective Pd(II)/CuCl 2-catalysed chlorocyclisation of sugar-derived aminoalkenitols has been accomplished. The requisite substrates were, in turn, prepared from chiral pool materials starting from the cheap and commercially available methyl-aD -gluco-and methyl-aD -galactopyranoside.
ChemInform, 2006
Dioxane derivatives R 0470 Novel Bicyclization of Unsaturated Polyols in PdCl 2-CuCl 2-AcOH Catal... more Dioxane derivatives R 0470 Novel Bicyclization of Unsaturated Polyols in PdCl 2-CuCl 2-AcOH Catalytic System.-A new route towards 1,4:2,5-dianhydroalditols by Pd 2+-catalyzed bicyclization of sugar-derived alkenitols is developed. The reaction requires an all-syn configuration of the vinylic stereotriad.
Tetrahedron, 2014
Lilac aldehydes are considered as principal olfactory molecules of lilac flowers. We have designe... more Lilac aldehydes are considered as principal olfactory molecules of lilac flowers. We have designed, prepared and evaluated two sets of their unnatural racemic analogues as pure diastereomers. While the synthesis of gem-dimethyl homologues starts from geranyl acetate, the preparation of methylene derivatives commences from linalyl acetate. The key Lewis and/or Brønsted acid catalysed cyclisation furnishes easily separable cis-/trans-tetrahydrofuranyl esters as common advanced intermediates. The subsequent functional group transformations lead to target aldehydes, alcohols, nitriles and olefins. Unlike the homologues possessing similar herbal scents, methylene derivatives exhibit woody and/or flowery odours. In the latter case, the sensory evaluation suggests the importance of relative stereochemistry and/or type of functional group on the odour character of respective compounds.
Cheminform, 2008
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Cheminform, 2006
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Acta Crystallographica Section C-crystal Structure Communications - ACTA CRYSTALLOGR C-CRYST STR, 2000
The absolute configuration at the new stereogenic centre during the key step of the total synthes... more The absolute configuration at the new stereogenic centre during the key step of the total synthesis was established byX-ray analysis of the title compound, C(7)H(15)NO(4)(+).Cl(-).
Tetrahedron: Asymmetry, 2000
The ®rst successful Pd(II)-catalysed aminocarbonylation of the highly substituted benzylaminoalke... more The ®rst successful Pd(II)-catalysed aminocarbonylation of the highly substituted benzylaminoalkene 5 allows the direct preparation of fused piperidine lactones 3 and 4, which are subsequently converted to the novel C-6 homologue of 1-deoxynojirimycin 1 and 1-deoxy-l-idonojirimycin 2. The study of the in¯uence of various catalytic conditions on the diastereoselectivity and product distribution of the key aminocarbonylation is presented.
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Papers by Peter Szolcsanyi