Synthesis of syn- and anti-tricyclo [4.1.0.02,4] heptan-5-ones and related compounds

A convenient entry to both title compounds 1 and 2, as well as to cis- and trans-4-iodomethyl-bicyclo [3.1.0]-hexan-2-ones 3and 4 and to 4-methyl-bicyclo [3.1.0]-hex-3-en-2-one 5 involving base-promoted reactions of cis- and -trans-3,4-diiodomethylcyclopentanones 6 and 7 is reported, and the behaviour of 6 and 7 towards different bases. bfv40bp4761b     

Cationic polymerization of 6,8-dioxabicyclo-[3.2.1]octane and 3,6,8-trioxabicyclo[3.2.1]octane

6,8-Dioxabicyclooctane (DBO) and 3,6,8-trioxabicyclooctane (TBO) underwent ring-opening polymerization when treated with PF₅ in dichloromethane at ?78°C. These conditions were outstandingly effective for the polymerization of these bicyclic monomers, as shown by systematic variation of catalyst, solvent, and temperature. Best results were 68–84% yields of poly-DBO, η_inh 0.26–0.33 dl/g, and ～100% yield of poly-TBO, η_inh 0.56–0.80 dl/g. The relationship of these results to those of previous investigators of DBO discussed.     

Die C8H12-Energiehyperfläche Thermolyse von syn- und anti-Tricyclo[4.2.0.02,5]octan. Experimentelle und theoretische Untersuchungen

The C₈H₁₂-Energy Hypersurface Thermolysis of syn- and anti-Tricyclo[4.2.0.0^2,5]octane. Experimental and Theoretical Studies The thermal behaviour of syn- and anti-tricyclo[4.2.0.0^2,5]octanes 9 and 10 in the gas phase as well as in solution is investigated. Two Mayn products are formed in parallel reactions: cis, cis-1,5-cyclooctadiene ( 11 ) and cis, trans-1,5-cyclooctadiene ( 15 ), the latter being partly isomerized to 11 under the reaction conditions. Minor products are cis-1,2-divinylcyclobutane ( 6 ), trans-1,2-divinylcyclobutane ( 16 ) and 4-vinyl-1-cyclohexene ( 17 ). Thermolysis of cis-1,2-divinylcyclobutane leads to small amounts of cis, trans-cyclooctadiene, presumably via a four-centre transition state. The tricyclics most likely prefer a stepwise isomerization. The decisive product-controlling factor seems to be the conformational mobility of intermediate diradicals. By comparison with the boat-Cope reaction of divinylcyclobutane the pericyclic six-centre transition state of this rearrangements is shown to lie energetically about 19 kcal/mol below the transition states in the thermolysis of 9 and 10 . The azo compound 12 on heating fragments predominantly in a concerted manner in contrast to the photolysis. Theoretical methods are applied to unveil structure and bonding in the supposed intermediate diradicals.     

Thermolysis of [1,2,4]triazolo[1,5-a]pyrimidine n-ylides

5,7-Dimethyl[1,2,4]triazolo[1,5-a]pyrimidinio-3-phenacylide ($\text{3}$) generated by the reaction of an iminium salt ($\text{2}$) with 1 eq. of triethylamine, underwent a new thermal ring cleavage of the triazole moiety to give the pyrimidine derivative. However reaction of $\text{2}$ with 2 eq. of triethylamine afforded the 2-iminooxazoline derivative. The iminooxazoline reacted with nucleophiles such as alcohols or amines to give imidazoles.     

Synthesis of 1,4-diazabicyclo[2.2.2]octane

Double intramolecular cyclization of N,N-bis(2-chloroethyl)-N-N-bis(2-cyanoethyl)ethylenediamine leads to 1,4-bis(2-cyanoethyl)-1,4-diazoniabicyclo[2.2.2]octane dichloride, which undergoes decyanoethylation to 1,4-diazabicyclo[2.2.2]octane when it is heated. The structures of the compounds were confirmed by their IR and PMR spectra.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 548–550, April, 1978.     

Polyesters containing bicyclo[2.2.2]octane and bicyclo[3.2.2]nonane rings

Polyesters containing bicyclo[2.2.2]octane and bicyclo[3.2.2]nonane rings are prepared from 1,4-bis(carboethoxy)bicyclo[2.2.2]octane, 1,4-bis(hydroxymethyl)bicyclo[2.2.2]-octane and the 1,5-disubstituted bicyclo[3.2.2]nonane analogs. These polyesters are compared to the related polymers containing 1,4-phenylene and trans-1,4-cyclohexylene rings in terms of their melting point, thermal stabilities and oxidative stabilities. The lower symmetry of the bicyclo[3.2.2]nonane ring produces lower-melting polymers than the other ring systems. The remaining three rings are approximately equivalent in their effect on the melting point of a polymer provided that no more than one bicyclo[2.2.2]octane ring is present per polymer repeat unit. Two such rings produce a highermelting polymer than any other combination. Both the thermal and oxidative stabilities of the polyesters is improved by the presence of the bicyclo rings. This is attributed to the rings providing an approximation of a ladder polymer.     

Stereoselective sulfur extrusion reaction of syn- and anti-10,20-dibromo-2,3,12,13-tetrathia[4.4]metacyclophanes to the corresponding syn- and anti-dithia[3.3]metacyclophanes

A new cyclophane, 10,20-dibromo-2,3,12,13-tetrathia[4.4]metacyclophane (1) , has been synthesized by the oxidative coupling reaction of 2,6-bis(mercaptomethyl)-1-bromobenzene with I₂. Both syn and anti isomers of 1 can be isolated at room temperature. The thermal sulfur extrusion reaction of anti- 1 with (Et₂N)₃P afforded anti-9,18-dibromo-2,11-dithia[3.3]metacyclophane, while syn- 1 gave 9,19-dibromo-2,11,12-trithia[3.4]metacyclophane. syn-9,18-Dibromo-2,11-dithia[3.3]metacyclophane was produced from the photochemical sulfur extrusion of syn- 1 with (MeO)₃P.     

Polymerization of 2,7,8-trioxabicyclo[3.2.1]octane and 2,8,9-trioxabicyclo[3.3.1]nonane

Treatment of 2,7,8-trioxabicyclo [3.2.1] octane (I) with electrophilic initiators gave polyorthoester composed of five- (70-86%), six-, and seven- (the sum, 14-30%) membered rings. Treatment of 2,8,9-trioxabicyclo [3.3.1]nonane (VI) with electrophilic initiators gave mainly oligomers. Trifluoromethane sulfonic acid in dichloromethane was particularly effective for the formation of dimer, 2,8,10,16,17,18-hexaoxatricyclo[11.3.1.1]hexadecane. The analysis of the structures of poly-I and oligomer-VI suggests that I and VI are polymerized through an S_N1 mechanism.