Simon Recnik

A simple synthesis of aplysinopsin analogues by dimethylamine substitution in N,N-(dimethylamino)methylidene derivatives of five-membered heterocycles

Abstract Some new aplysinopsin analogues were prepared by a simple coupling of N , N -(dimethylamino)methylidene substituted hydantoin, thiohydantoin, and thiazolone derivatives, with indole derivatives. Configuration around the exocyclic CC double bond was determined on the basis of long-range heteronuclear coupling constants using 2D HMBC correlation technique.

Stereoselective synthesis of (1R,3R,4R)-3-(1,2,4-triazolo[4,3-x]azin-3-yl)-1,7,7-trimethylbicyclo[2.2.1]heptan-2-ones

Abstract (1R,3R,4R)-3-(1,2,4-Triazolo[4,3-x]azin-3-yl)-1,7,7-trimethylbicyclo[2.2.1]heptan-2-ones were prepared in 68–94% d.e. in three steps from (1R)-(+)-camphor via coupling of (1R,4R)-3-[(E)-(dimethylamino)methylidene]-1,7,7-trimethylbicyclo[2.2.1]heptan-2-one with hydrazinoazines followed by oxidative cyclisation of the intermediate hydrazones with methanolic bromine. The structures were determined by 2D NMR techniques and NOESY spectroscopy as well as by X-ray diffraction.

1,3-Dipolar Cycloadditions to (5Z)-1-Acyl-5-(cyanomethylidene)- imidazolidine-2,4-diones: Synthesis and Transformations of Spirohydantoin Derivatives

Cycloadditions of various 1,3-dipoles to (5Z)-1-acyl-5-(cyanomethylidene)-3-methylimidazolidine-2,4-diones 8 or 9, prepared in 3 steps from hydantoin (1) (Schemes 1 and 2), were studied. In all cases, reactions proceeded regio- and stereoselectively. The type of product depended on the 1,3-dipole and/or dipolarophile employed as well as on reaction conditions. Thus, with stable dipoles under neutral conditions, spirohydantoin derivatives 12 – 16 were obtained (Scheme 2), while under basic or acidic conditions, pyrazole- or isoxazole-5-carboxamides 18 and 23 – 26 and carboxylate 27 were formed via aromatization of the newly formed dihydroazole ring, followed by the simultaneous cleavage of the hydantoin ring (Schemes 3 – 5).

Synthesis and Reactivity of (Z)-3-Benzoylamino-4-dimethylamino-2-oxo-3-butene. Preparation of 1-Aryl- and 1-Heteroaryl-substituted 4-Benzoylamino-5-methyl-1H-pyrazoles

(Z)-3-Benzoylamino-4-dimethylamino-2-oxo-3-butene (4), prepared from 1-benzoylamino-2-propanone (3) and N,N-dimethylformamide dimethyl acetal, was converted regioselectively by reaction with a series of hydrazines (5) into 1-substituted 4-benzoylamino-5-methyl-1H-pyrazoles (8). Reactions of 4 with primary amines (10) and with dimethylbarbituric acid (12) afforded the dimethylamine substitution products (11) and (13), respectively. Treatment of the butenone (13) with ammonia furnished tetrahydropyrido[2,3-d]pyrimidine derivative (14).

Ring Contractions of 4‐Oxoquinolizine‐3‐diazonium Tetrafluoroborates, by an Aza Wolff Rearrangement, to Alkyl Indolizine‐3‐carboxylates

The 1-substituted 3-amino-4H-quinolizin-4-ones 13, available in two steps from 10 and methyl (Z)-2-benzyloxycarbonylamino-3-(dimethylamino)propenoate (11), were diazotized to give the stable diazonium tetrafluoroborates 7a and 7b. Heating of these diazonium salts in alcohols gave mixtures of 3-unsubstituted quinolizine derivatives 8a and 8b and the alkyl indolizine-3-carboxylates 9a−h. The ratio of the two types of products 8 and 9 was dependent on the type of alcohol employed. Thus, treatment of 7a or 7b with 2-propanol predominantly resulted in the 3-unsubstituted quinolizinones 8, while treatment of 7a or 7b with primary alcohols gave the indolizine-3-carboxylates 9 as the major products in most cases. The transformation of the 4-oxoquinolizine-3-diazonium tetrafluoroborates 7a and 7b into the alkyl indolizine-3-carboxylates 9a−h represents the first example of a Wolff rearrangement in the fused cyclic α-diazoamide series.

Ring Contractions of 3-Azido-4H-quinolizin-4-ones and 3-Azido-4H-azino[1,2–x]pyrimidin-4-ones: a Novel Approach to 3-Aminoindolizines and their Aza Analogues

Thermal transformations of 3-azido-4H-quinolizin-4-ones 4a,b and 3-azido-4H-azino[1,2–x]pyrimidin-4-ones 4c,d, available from the corresponding heteroarylamines 2a–d, were studied. The reaction products were mostly dependent on the solvent. Thus, heating of 3-azido-1-cyano-4H-quinolizin-4-one (4a) in toluene afforded 2-(pyridin-2-yl)fumaronitrile 5a, whereas 3-amino-1-cyano-4H-quinolizin-4-one (8) was obtained on treatment of 4a in a mixture of toluene and trifluoroacetic anhydride. However, heating of 4a in acetic anhydride and in acetic acid resulted in a ring contraction to produce 3-(diacetylamino)indolizine-1-carbonitrile 6a and 3-(acetylamino)indolizine-1-carbonitrile 7a, respectively. Similarly, ring contractions took place on heating ethyl 3-azido-4-oxo-4H-quinolizin-1-carboxylate 4b and 3-azido-4H-azino[1,2–x]pyrimidin-4-ones 4c,d in acetic anhydride or acetic acid to produce the N-acetylated 3-aminoindolizine derivatives 6b, 7b and 3-aminoimidazo[1,2–x]azine derivatives 6c,d in 30–89% yields. The structures of compounds 5–8 were determined by NMR spectroscopy and X-ray diffraction.

Stereoselective Synthesis of 5-((Z)-Heteroarylmethylidene) Substituted Hydantoins and Thiohydantoins as Aplysinopsin Analogs*

3-Substituted 5-[(Z)-heteroarylmethylidene]imidazolidine-2,4-dione and 5-[(Z)-heteroarylmethylidene]- 2-thiooxoimidazolidin-4-one derivatives were prepared stereoselectively by coupling of 5-(dimethylamino)methylidene substituted hydantoin and thiohydantoin derivatives with carbocyclic and heterocyclic C-nucleophiles.Configuration around the exocyclic C=C double bond was determined by NMR, using NOESY and 2D HMBC techniques.

Reactions of Quinolizine- and Pyridino(1,2-a)pyrimidine-3-diazonium Tetrafluoroborates with Aliphatic Amines*

Keywords Reactions of 1-cyano-4-oxo-4H-quinolizine-3-diazonium tetrafluoroborate (1a) and 4-oxo-4Hpyridino[ 1,2-a]pyrimidine-3-diazonium tetrafluoroborate (1b) with aliphatic amines 2a - g were studied. Treatment of heteroaryldiazonium salts 1 with secondary amines 2a - d afforded the corresponding N-alkyl-N’-heteroaryltriazenes 3a - h in high yields. On the other hand, reactions of 1a with aliphatic primary amines 2e - g resulted in an unexpected rearrangements into the corresponding picolinic acid N-alkylcarboxamides 4a - c.