Addition initiated ring closure: synthesis of substituted spiro[2.4]hepta-4,6-dienes via cyclopentadiene intermediates from fulvene precursors

1984 ◽  
Vol 62 (11) ◽  
pp. 2451-2455 ◽  
Author(s):  
Kazimierz Antczak ◽  
John F. Kingston ◽  
Alex G. Fallis
Keyword(s):  
Intramolecular Cyclization ◽  
Nucleophilic Addition ◽  
Ring Closure

The reactivity of the epoxy-fulvene 1, prepared by pyrrolidine catalyzed condensation of cyclopentadiene and epoxybutanone, has been examined with various nucleophiles. It is a versatile intermediate for the preparation of spiro[2.4]hepta-4,6-diene synthons via nucleophilic addition to the C6 position of the fulvene followed by intramolecular cyclization of the substituted cyclopentadiene anion generated insitu.

scholarly journals Isolation of a post-PKS C–C branching jadomycin from S. venezuelae ISP5230 in the presence of 8-aminooctanoic acid

2018 ◽  
Vol 96 (7) ◽  
pp. 760-764 ◽  
Author(s):  
Jeanna M. MacLeod ◽  
Stephanie M. Forget ◽  
Camilo F. Martinez-Farina ◽  
David L. Jakeman
Keyword(s):  
Natural Products ◽  
Amino Acid ◽  
Natural Product ◽  
Intramolecular Cyclization ◽  
Nucleophilic Addition ◽  
Culture Method ◽  
Amino Acid Supplementation ◽  
Acid Supplementation

The jadomycin family of natural products was first identified and characterized by Vining and co-workers at Dalhousie University in the 1990s. Herein, we report findings from a recently developed co-amino acid supplementation culture method with S. venezuelae ISP5230 using 8-aminooctanoic acid, where the major natural product was a jadomycin variant omitting an E-ring (1). These results reinforce that the 3a position is susceptible to nucleophilic addition by cellular metabolites in jadomycin biosynthesis when intramolecular cyclization is unfavorable. Further, the cytotoxicity data for several unsubstituted E-ring jadomycins are reported and discussed.

Studies on double acylation of aromatic hydrocarbons. XI. A total synthesis of 5,6-Dihydro-4H-benz[de]anthracene

1972 ◽  
Vol 25 (7) ◽  
pp. 1521 ◽  
Author(s):  
A Rahman ◽  
BM Vuano ◽  
NM Rodriguez
Keyword(s):  
Total Synthesis ◽  
Propionic Acid ◽  
Intramolecular Cyclization ◽  
Butyric Acid ◽  
Aromatic Hydrocarbons ◽  
Dibasic Acid ◽  
Membered Ring ◽  
Ring Closure ◽  
Partial Synthesis

Starting from ethyl 3-(1-naphthyl)propionate (1), the dibasic acid 4-(4-carboxy-ethyl-I-naphthyl)butyric acid (3) was prepared, which served as a key compound for the synthesis of 5,6-dihydro-4H-benz[de]anthraoene (6) by a double intramolecular cyclization. The monocyolization of the dibasic acid (3) gave rise by a preferential six-membered ring closure, to 3-(1-oxo-1,2,3,4-tetrahydro-9-phenanthryl)propionic acid (7). A partial synthesis of 5,6-dihydro-4H-benz[de]anthracene (6), by succinoylation of perinaphthane followed by usual synthetic steps, is reported as confirmatory evidence of the identity of (6) obtained by double cyclization of the diacid. Some aspects of the orientation of intramolecular acylation are discussed.

Preparation of 1,3-thiazines: Sulphur analogues of nucleic acid pyrimidine bases

1970 ◽  
Vol 23 (1) ◽  
pp. 51 ◽  
Author(s):  
EN Cain ◽  
RN Warrener
Keyword(s):  
Acid Hydrolysis ◽  
Intramolecular Cyclization ◽  
Ring Closure ◽  
Synthetic Methods ◽  
Cyclization Reactions ◽  
Dithiocarbamic Acid ◽  
Pyrimidine Bases ◽  
Propiolic Acid ◽  
Hydrolysis Of ◽  
Acetylenic Acids

Sulphur analogues of uracil and thymine have been prepased, in which the N1 atom of the pyrimidine base has been replaced by a sulphur atom. A number of general synthetic methods are described for the synthesis of these 1,3-thiazines. The uracil analogues were prepared from the related 2-thio-1,3-thiazines, by acid hydrolysis of the 2-alkylthio derivative. 3,4-Dihydro-4-oxo-2-thio-2H-1,3-thiazine, its N-methyl and N-ethyl derivatives were obtained by cyclization of the addition compound resulting from the reaction of propiolic acid and the appropriate dithiocarbamic acid. The generality of this reaction, when propiolic acid is replaced with other acetylenic acids or their related esters, is discussed. The crystalline addition compounds obtained from dithiocarbamic acid and either propiolic acid or methyl propiolate were all shown by p.m.r, spectroscopy to have cis stereo-chemistry. The thymine analogues were prepared by an alternative route, which utilized the intramolecular cyclization of S-ethyl-N-(β-methoxymethacryloyl)dithiocarbamate to form 2-ethylthio-6-methyl-4-oxo-4H-1,3-thiazine, followed by acid hydrolysis of the 2-ethylthio group. Related intramolecular cyclization reactions of N-acyl-dithiocarbamates formed the 5-acetyl-, the 5-cyano-6-methyl-, the 5-cyano-6-ethyl-, and the 6-methyl-2-ethylthio-1,3-thiazine derivatives. A third approach involved the successful acid catalysed ring-opening-ring- closure of a. 4-oxo-2-thio-1,3-oxazine to the isomeric 2,4-dioxo-1,3-thiazine.

scholarly journals Efficient Tandem Addition/Cyclization for Access to 2,4-Diarylquinazolines via Catalytic Carbopalladation of Nitriles

Molecules ◽  
2019 ◽  
Vol 24 (3) ◽  
pp. 463
Author(s):  
Julin Gong ◽  
Kun Hu ◽  
Yetong Zhang ◽  
Yinlin Shao ◽  
Tianxing Cheng ◽  
...  
Keyword(s):  
Intramolecular Cyclization ◽  
Nucleophilic Addition ◽  
Functional Group ◽  
Synthetic Pathway ◽  
Arylboronic Acids ◽  
Palladium Catalyzed ◽  
Plausible Mechanism

The first example of the palladium-catalyzed tandem addition/cyclization of 2-(benzylidenamino)benzonitriles with arylboronic acids has been developed. This transformation features good functional group tolerance and provides an alternative synthetic pathway to access 2,4-diarylquinazolines in moderate to good yields. A plausible mechanism for the formation of 2,4-diarylquinazolines involving sequential nucleophilic addition followed by an intramolecular cyclization is proposed.

scholarly journals Synthesis of New Bis(spiro-β-lactams) via Interaction of Methyl 1-Bromocycloalcanecarboxylates with Zinc and N,N′-Bis(arylmethylidene)benzidines

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
N. F. Kirillov ◽  
E. A. Nikiforova ◽  
D. V. Baibarodskikh ◽  
T. A. Zakharova ◽  
L. S. Govorushkin
Keyword(s):  
Nitrogen Atom ◽  
Carbonyl Group ◽  
Nucleophilic Addition ◽  
Ring Closure ◽  
Amide Nitrogen ◽  
Ester Carbonyl ◽  
Ester Carbonyl Group ◽  
Amide Nitrogen Atom

Interaction of the Reformatsky reagents, prepared from methyl 1-bromocyclopentane-1-carboxylate or methyl 1-bromocyclohexane-1-carboxylate, with N,N′-bis(arylmethylidene)benzidines has given rise to a set of intermediates as a result of nucleophilic addition to the C=N group of a substrate. Further intramolecular attack of the amide nitrogen atom onto the ester carbonyl group is responsible for the ring closure, which affords two series of spirocompounds: 2,2′-([1,1′-biphenyl]-4,4′-diyl)bis(3-aryl-2-azaspiro[3.4]octan-1-one) or 2,2′-([1,1′-biphenyl]-4,4′-diyl)bis(3-aryl-2-azaspiro[3.5]nonan-1-ones).

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