Ring-opening processes in the 8-oxabicyclo[3.2.1]octane ring system

1983 ◽  
Vol 48 (25) ◽  
pp. 4882-4887 ◽  
Author(s):  
Vijaya Sampath ◽  
Neil E. Schore
Keyword(s):  
Ring Opening ◽  
Ring System

Resolving the Mystery of Ring Opening in the Synthesis of Benzo[d][1, 3]oxazin-4-one and Quinazolin-4(3H)-one

2019 ◽  
Vol 16 (11) ◽  
pp. 898-905
Author(s):  
Harun Patel ◽  
Rahul Pawara ◽  
Sanjay Surana
Keyword(s):  
Characteristic Feature ◽  
Ring Opening ◽  
Biological Activities ◽  
Heterocyclic Ring ◽  
Ring System ◽  
Time Saving ◽  
Fusion Strategy ◽  
Good Template ◽  
Lead Generation

Quinazoline is the six-membered heterocyclic ring system reported for its versatile biological activities. This characteristic feature of quinazoline makes it a good template for a lead generation library. Ring opening is one of the major concerns in the synthesis of quinazolin-4(3H)-one that results in diamide formation. Here, alternative fusion strategy is reported, which is a time-saving and costeffective method to overcome the ring opening problem associated with the synthesis of benzo[ d][1,3]oxazin-4-one and quinazolin-4(3H)-one.

Some Transformations of Adducts of 3,6-Dimethoxy-4,5-methylenedioxy-1,2-didehydrobenzene and Furans. An Approach to the 5,8-Dimethoxy-6,7-methylenedioxynaphtho[2,3-c]furan-4,9-dione Ring System of Ventilone A

1998 ◽  
Vol 51 (5) ◽  
pp. 409 ◽  
Author(s):  
Jarrod H. Buttery ◽  
Dieter Wege
Keyword(s):  
Ring Opening ◽  
Ring System ◽  
Subsequent Oxidation ◽  
Naturally Occurring

Adducts derived from the aryne 3,6-dimethoxy-4,5-methylenedioxy-1,2-didehydrobenzene (19) with furan and 2-methoxyfuran have been converted into 5,8-dimethoxy-6,7-methylenedioxy-1,2-naphthoquinone (22) and 5,8-dimethoxy-6,7-methylenedioxy-1,4-naphthoquinone (24) respectively. The trapping of (19) with 1H,3H-furo[3,4-c]furan (38) yielded an unstable adduct (37), which on acid-catalysed ring opening and subsequent oxidation was transformed into 5,8-dimethoxy-6,7-methylenedioxynaphtho[2,3-c]furan-4,9-dione (36), a compound possessing the ring system of the naturally occurring quinone ventilone A.

Carbon–nitrogen bond cleavage of pyridine with two molecular substituted allenoates: access to 2-arylpyrimidin-4(3H)-one

2018 ◽  
Vol 54 (100) ◽  
pp. 14128-14131 ◽  
Author(s):  
Tao Jin ◽  
Hongdong Yuan ◽  
Shikuan Su ◽  
Xueshun Jia ◽  
Chunju Li ◽  
...  
Keyword(s):  
Benzene Ring ◽  
Ring Opening ◽  
Pyridine Ring ◽  
Bond Cleavage ◽  
Ring System ◽  
Nitrogen Bond

A DABCO-catalyzed annulation reaction of pyridin-2-amine and substituted allenoates enables the ring-opening of a pyridine ring system and the formation of two new rings including a pyrimidinone ring and a benzene ring.

Improvement in zinc complexes bearing Schiff base in ring-opening polymerization of ε-caprolactone: A five-membered ring system

Polymer ◽  
2019 ◽  
Vol 182 ◽  
pp. 121812 ◽  
Author(s):  
Feng-Jie Lai ◽  
Li-Ling Chiu ◽  
Chieh-Ling Lee ◽  
Wei-Yi Lu ◽  
Yi-Chun Lai ◽  
...  
Keyword(s):  
Schiff Base ◽  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Ring System ◽  
Membered Ring ◽  
Zinc Complexes

The preparation of a stable 8-oxatricyclo[4,3,0,07,9]nona-2,4-diene and an evaluation of its potential as a source for the photochemical generation of oxiren

1981 ◽  
Vol 34 (4) ◽  
pp. 855 ◽  
Author(s):  
RN Warrener ◽  
RA Russell ◽  
RYS Tan
Keyword(s):  
Hydrogen Peroxide ◽  
Double Bond ◽  
Photochemical Reaction ◽  
Ring Opening ◽  
Thermal Conditions ◽  
Ring System ◽  
Crystalline Solid ◽  
Mercuric Oxide ◽  
Azo Compound ◽  
Photochemical Generation

The synthesis of 2-methyl-3,4,5-triphenyl-8-oxatricyclo[4,3,0,07,9]nona-2,4-diene (14) is described, the first stable member of this ring system. Preparation of (14) was achieved by reacting dibenzyl diazenedicarboxylate with 2-methyl-3,4,5-triphenylbicyclo[4,2,0]octa-2,4,7-triene (29) to form the adduct (30a), which was selectively epoxidized at the cyclobutenyl double bond with 3-chloroperbenzoic to yield the epoxide (32a). Removal of the benzyl groups (H2/Pd) from the hydrazo bridge of (32a), followed by oxidation (red mercuric oxide or hydrogen peroxide) yielded the putative azo compound (33) which spontaneously lost dinitrogen, even at -78�, to yield (14) as a crystalline solid, m.p. 128�. While (14) has the potential to undergo 1,2-photoaromatization to yield oxiren (4a), this is not realized and ring-opening to the cyclic epoxide (34) is the major photochemical reaction observed under various ultraviolet irradiation conditions. Isomerization of (14) into (34) also occurs under thermal conditions. The 1H n.m.r, spectra of (14) as well as its trapping with dienophiles is discussed.

Cyclophanes. VI. The synthesis of [2,2](3,3')biphenylparacyclophanedienes

1976 ◽  
Vol 29 (6) ◽  
pp. 1267 ◽  
Author(s):  
PJ Jessup ◽  
JA Reiss
Keyword(s):  
Ring Opening ◽  
Ring System ◽  
Ring Contraction ◽  
Stevens Rearrangement ◽  
Ring Opening Reaction ◽  
Disubstituted Benzene ◽  
Contraction Procedure

The preparations of [2,2](3,3')biphenylparacyclophane-1,9-dine (19) and a dimethyl derivative (20) synthesized by a ring-contraction procedure of the corresponding dithiacyclophanes (11) and (12) are reported. Both dienes (19) and (20) photocyclized under oxidative conditions to the benzo[ghi]- perylenes (21) and (22). Difficulties associated with the Stevens rearrangement in cyclophanes containing a para-disubstituted benzene moiety have been rationalized in terms of a competing ring- opening reaction. Several other reactions of the biphenylparacylophane ring system are reported, and the stereochemistry of the macrocycle is discussed.

Synthesis and Applications of Cyclopropanones and their Equivalents as Three-Carbon Building Blocks in Organic Synthesis

Synthesis ◽  
2021 ◽  
Author(s):  
Yujin Jang ◽  
Roger Machin-Rivera ◽  
Vincent Lindsay
Keyword(s):  
Organic Synthesis ◽  
Ring Opening ◽  
Building Blocks ◽  
Ring Expansion ◽  
Ring System ◽  
Small Ring ◽  
Future Directions ◽  
Highly Strained ◽  
And Storage

Cyclopropanone derivatives constitute highly strained cycloalkanones with promising applications as three-carbon building blocks in organic synthesis. Due to the presence of a ketone in such a small ring system, all C–C bonds and the carbonyl group are considered to be labile in suitable conditions, leading to a wide variety of synthetic disconnections, including nucleophilic addition, ring expansion, ring-opening and (formal) cycloaddition. Despite their synthetic potential, the widespread adoption of cyclopropanones as substrates has been considerably hampered by the difficulties associated with the preparation and storage of such unstable compounds, prompting the development of cyclopropanone surrogates that can equilibrate to parent ketone in situ via elimination. This review summarizes the syntheses and applications of cyclopropanone derivatives and their equivalents, and offers a perspective of the state of the field as well as its expected future directions.

Overcrowded aminophospanitrenes: a case study

2017 ◽  
Vol 72 (11) ◽  
pp. 865-871
Author(s):  
Jürgen Tirrée ◽  
Alexander V. Ruban ◽  
Martin Nieger ◽  
Claudia Li ◽  
László Nyulászi ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Ring Opening ◽  
Ring System ◽  
Thermally Induced ◽  
Induced Decomposition

AbstractIn a search for stable phosphinonitrenes generated by thermally induced decomposition of the azidophosphines 8a, b, different cyclodiphosp(V)azene products were generated. While in the case of 8a the expected phosphinonitrene dimer 10 could be obtained, from 8b, which has the sterically more demanding TMP substituents, product 11, was obtained and characterized. DFT calculations have revealed that the primarily formed phosphinonitrene 9b is unstable against loss of TMP˙, and the resulting radical dimerizes to the biradicaloid 1,3-diaza-2,4-diphosphetane-2,4-diyl 13. Compound 13 then dimerizes after ring opening, yielding in the ring system, which provides the final product upon reaction with the starting azidophosphine.

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