Synthesis of macrocyclic terpenoids by intramolecular cyclization V. transannular reactions of hedycaryol isomers

Thermal rearrangement and acid-catalyzed cyclization of all possible geometrical isomers of hedycaryol were investigated. From the stereochemistry of the products, the reacting conformations were deduced. While three (E,E-, E,Z- AND Z,E-) isomers reacted through the crossed conformations, Z,Z-isomer yielded products $\text{via}$ parallel conformations. The thermal reaction at higher temperatures revealed the additional pathways involving Cope rearrangement of elemols. All possible stereoisomers of elemol were synthesized. The structure of “epielemol” has to be revised.     

Synthesis of macrocyclic terpenoids by intramolecular cyclization VI. Synthesis of 3Z-cembrene A and cembrenene

Two 14-membered diterpenes, 3Z-cembrene A and cembrenene, isolated from a termite and a soft coral, respectively, were synthesized by the anion-induced cyclization of geranylgeranyl phenyl sulfide.     

Synthesis of macrocyclic terpenoids by intramolecular cyclization VII. Total synthesis of (±)-cubitene

Stereoselective total synthesis of (±)-cubitene, a diterpene isolated from termite soldiers, and its stereisomer has been achieved utilizing the anion-induced intramolecular cyclization.     

Synthesis of macrocyclic terpenoids by intramolecular carbonyl coupling: flexibilene and humulene

Total syntheses of two macrocyclic sesquiterpene hydrocarbons, humulene (1) and flexibilene (2) are discussed in detail. Both were prepared in high overall yield by titanium-induced cyclization of the appropriate keto aldehyde precursors (4 and 9, respectively), themselves obtained by coupling of the vinylic zirconium reagent 22 with pi-allylpalladiums 26 and 23.     

Synthesis of macrocyclic terpenoids by intramolecular cyclization IX. Total synthesis of (±)-obscuronatin and (±)-biflora-4,10(19),15-triene.

Stereoselective total synthesis of (±)-obscuronatin, a marine diterpene with a 10-membered ring, has been achieved utilizing the anion-induced cyclization of an acyclic epoxy sulfide. The synthesis confirmed the stereostructure of the natural product.     

Synthesis of macrocyclic esters by catalytic cyclization

Macrocyclic esters were synthesized in good yield through catalytic cyclization by metal salts of glycol monosuccinates. The procedure is an improvement over catalytic depolymerization for the preparation of cyclic compounds, as developed by Carothers.     

Synthesis of novel macrocyclic ether-ester compounds via the intramolecular cyclization of oligoethylene glycol monocarboxymethyl ethers.

By treating of the oligoethylene glycol monocarboxymethyl ethers with p-toluenesulfonyl chloride in the presence of alkali metal carbonates, novel macrocyclic polyether-monoester compounds were obtained in moderate yield.     

Synthesis of macrocyclic terpenoids by intramolecular cyclization VIII. synthesis o cembra-3E, 7E, 11E, 15(17)-tetraen-trans-16, 2-olide

A synthesis of the naturally-occurring title compound has been accomplished. It represents the first success in the synthesis of the naturally-occurring cembranolides.     

Synthesis of riccardin B by nickel-catalyzed intramolecular cyclization

Riccardin B, a macrocyclic bis(bibenzyl) possessing cytotoxic activity, and its dehydroxy derivative were synthesized in high yields using the nickel-catalyzed intramolecular coupling of the acyclic precursors.     

Synthesis of 2,5-disubstituted 6-azaindoles from substituted aziridines via intramolecular cyclization

A new and efficient preparation of pharmacologically and biologically important 2,5-disubstituted 6-azaindoles was achieved from cyclizations of aziridin-2-yl dipropargylic alcohols as adducts of two propargyl groups to ethyl 1-benzylaziridine-2-carboxylate. The sequential cyclizations include pyrrole formation and a novel base-catalyzed intramolecular acetylenic Schmidt reaction.     

Synthesis and intramolecular cyclization of bisthiadiazinylmethane derivatives

Bisthiadiazinylmethane derivatives obtained from 1,2,6-thiadiazine 1,1-dioxides and formaldehyde, undergo unusual intramolecular cyclizations to thiadiazino [4,3-g] [2,1,3] benzothiadiazine tetraoxides. The structures of the newly synthesized compounds are discussed on the basis of ¹H and ¹³C-NMR data and X-ray analysis.     

Synthesis of tricyclic and tetracyclic sultones by Pd-catalyzed intramolecular cyclization

A new efficient synthesis of aromatic six-membered ring sultones by the implementation of ligand-free Pd-catalyzed intramolecular cyclization of aromatic sulfonates derived from various bromo phenols and naphthols is described.     

Synthesis of dipyrrolo-diazepine derivatives via intramolecular alkyne cyclization

A regioselective approach was developed for the synthesis of dipyrrolo-diazepine derivatives. The synthetic route to dipyrrolo-diazepines first involves the synthesis of dipyrromethanes, followed by reaction of propargyl bromide in the presence of NaH to attach one alkyne functionality to the pyrrole nitrogen atom. Intramolecular heterocyclization with NaH in DMF between the alkyne functionality and pyrrole nitrogen atom gave the desired structures in good yields.     

Synthesis of chlorine-containing benzisoindolinium salts by base-catalyzed intramolecular cyclization of ammonium salts

It was shown that dialkylpropargyl/3-(p-chlorophenyl)-2,3-dichloroallyl/ammonium salts in an aqueous alkali medium undergo cyclization-dehydrochlorination to give chlorine-containing benzisoindolinium salts. When the ammonium salt contains simultaneously 3-phenyl (or vinyl)propargyl and 3-(p-chlorophenyl)-2,3-dichloroallyl groups, only the latter enters into the cyclization as the diene fragment.Communication 201 of the series Research on amines and ammonium compounds. See [1] for Communication 197.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1481–1483, November, 1988.