seven-membered

Depending on the reaction conditions, this process can theoretically lead to the corresponding isomeric five-, six-, and seven-membered cyclic acetals: 1,3-dioxolanes, 1,3-dioxanes, and 1,3-dioxepanes, respectively.

In the HMBC and HSQC spectra, correlations from H-4 to C-23, from H-l, H-2, and H-4 to C-3, from H-10 to C-l, C-2, from H-4 to C-10, and from H-24 to C-4, C-5, and C-10 were observed and suggested a seven-membered lactone ring in compound 1 (Fig.

The mechanistic pathway of the reaction of benzylidenepyrazolinones 255 with aminothiophenol derivatives involves the formation of intermediate Michael adduct 256 via nucleophilic attack of the sulphydryl group on the [beta]-carbon atom of the double bond of 255 which is rendered electrophilic due to vinyl-carbonyl conjugation (i.e., when substituents are present in an [alpha], [beta]-unsaturated ketone, only the nucleophilic addition of the mercapto group to the [beta]-carbon atom takes place, followed by condensation of the carbonyl group with the aromatic primary amine to give a seven-membered ring system) and leads to the formation of the benzothiazepines 257.

This may be due to the fact that in solution either averaging of the confo-rmational possibilities is not complete or the twisted biphenyls of the dioxybiphenyl seven-membered spiro rings attend kinetically-stable conformations due to the intrinsic nature of the substitution groups.

These seven-membered heterocycles have been prepared by a variety of different routes, but the preparation of a completely unsaturated thiazepinone ring has not been reported.

It is a seven-membered ring with two identical -CO-O- groups.

Finally, we wanted to enlarge the central six-membered ring of the lactone structure into a seven-membered heterocycle, containing either oxygen or sulfur atom and bearing an appended phenyl ring.

Pisiferdiol having a unique seven-membered ring showed more specific PP2C activation activity (1.3-fold at 100 [micro]M) than pisiferic acid having a normal six-membered ring and oleic acid, which is known to activate PP2C.

They have divided the two-volume text into sections dealing with synthesis of allenes, covering isomerization reactions, metal-mediated synthesis, transition metal-catalyzed synthesis, and enantoselective synthesis; special classes of allenes, including allenic hydrocarbons, cyclic allenes up to seven-membered rings, acceptor- and donor-substituted allenes, and allenylmetal compounds; reactions of allenes, dealing with ionic additions, free radical addition, cycloadditions, cyclization, transition metal-catalyzed cross-couplings and cycloisomerizations, and oxidation; and, finally, applications such as allenic natural products and pharmaceuticals, allenes in natural product synthesis, and enyne-allenes.

Five-, six- and seven-membered ring and bi- and polycyclic lactones and lactams can be synthesized in good yield and selectivity by palladium complex-catalyzed intramolecular cyclocarbonylation reactions.