1.3- Dioxole ring

The anomeric effect is not limited to six-membered ring compounds. In five-membered rings the anomeric effect can affect both ring and substiment conformation. The 1,3-dioxole ring adopts a puckered conformation as a result of an anomeric effect. Similar effects are observed, although attenuated, in l,3-benzodioxoles. °... 

Dioxole ring from 2 diazo oxide molecules O... 

In terms of other sites of metabolism, we are looking at the metabolism in the dioxole ring and in dealkylation. We have seen some interesting things, but I could not comment on this right now. With respect to the alpha-ethyl, I think that the parent compound is probably the one that is active. 

Nichols, D. E., and Kostuba, L. J. (1979) Steric effects of substituents on phenethylamine hallucinogens. 3,4-(Methylenedioxy)amphetamine analogues alkylated on the dioxole ring. J. Med. Chem., 22 1264-1267. 

Other dioxole monomers and polymers have been prepared from halogenated dioxoles with different substituents in the 2,4, and 5 positions of the dioxole ring. 

Table 2.1 lists a number of dioxole monomers and indicates their ability to homopolymerize and/or copolymerize with TFE in CFC-113 solution. The copolymerization of dioxoles with chlorine in the 4 and 5 position of the dioxole ring further demonstrates the very high reactivity of this ring system. Thus an almost infinite number of dioxole polymers can be prepared with one or more comonomers in varying proportions. We have chosen to focus our present work on copolymers of TFE and PDD to preserve the outstanding thermal and chemical properties of perfluorinated polymers. At this point it should be noted that fully fluorinated ethers are nonbasic and effectively possess the same chemical inermess as fluorinated alkanes. Perfluorinated ether groups in polymers are even less reactive as a result of their inaccessibility to chemical reagents. 

FEP and PFA despite being melt-processible are crystalline (between 50 and 70%). The crystallinity results in poor optical properties (low clarity) and a very poor solubility in organic solvents. The latter makes the preparation of thin optical coatings exceedingly difficult.10 TEFLON AF, an amorphous fluoropolymer, contains in its molecule a bulky dioxole ring, which hinders crystallization. As a result, the polymer has an exceptionally high clarity and excellent optical properties. Its refractive index is the lowest of any plastic.11... 

Heterocycles of this type occur widely. The benzo[l,3]dioxole ring system is often found in natural products and their degradation products, e.g., sesamol 38 lipoic acid 39 is a naturally occurring 1,2-dithiolane derivative. The 1,3-dithiolanes 40 are commonly known as 1,3-dithioacetals and have been extensively used in carbonyl group chemistry. In the absence of cyclic conjugation, ring sulfur atoms can readily exist in higher oxidation states as, for example, in the oxathiole S, -dioxide 41. 1,3,2-Dioxathiolane A-oxides 42 (cyclic sulfites) and 1,3,2-dioxathiolane A,A-dioxides (cyclic sulfates) are useful as synthetic equivalents of epoxides. 

A large number of new reports of reactions of this type have appeared, the majority of which involve reaction between a 1,2-diol or equivalent and an aldehyde, ketone, or other component that supplies C-2 of the resulting dioxole ring. Synthesis of aromatic fused dioxoles will be considered first before dioxolanes and dioxolanones. 

Similar conclusions have been reached for the third commercially important fully fiuorinated polymer, namely the copolymer of tetrafiuoroethylene and per-fiuoropropyl vinyl ether (317-320). This is not imexpected, because this material typically contains approximately 2 mol% of the vinyl ether. Irradiation at elevated temperatures by electron beam or with y-rays resulted in increased jdelds of cross-links. Finally, Forsythe and co-workers (321) have also reported the radiation chemistry of members of the Teflon AF DuPont family of thermoplastics, and found that degradation proceeded through loss of hexafiuoroacetone of the dioxole ring, leading to chain-scission reactions. 

The l,3-dioxol-2-one ring in these compounds is relatively stable, thereby allowing acetylation, reduction, and the replacement of the keto group by a thione group giving photochromes 243-245 (02IZV1588, 05IZV1299). 

The nomenclature used here corresponds to that used in Chemical Abstracts which utilizes the style cyclobuta-, penta-, benzo-, etc., di(heterocycle) if the fused rings are similar. Otherwise the form of heterocycle [cyclopenta-etc.] heterocycle is used. Compound 1 is described as a benzodipyrrole rather than a pyrroloindole, the correct name being benzo[l,2- 5,4- ]dipyrrole. Compound 2 is named as a thieno[3,2- ]benzothiazole and compound 3 is named as a furo[3, 2 ]cyclopenta[l,2-i/l-l,3-dioxole. 

In addition to the alkenyldioxolanes, 4-methylenedioxolane (87) and dioxoles (88) and (89) can be utilized to produce heterocyclic polymers containing this ring system. In a comparative study on the cationic polymerization of these monomers (79MI11105) it was found that the order of reactivity is (87) > (88) > (89). In these polymerizations, ring-opening reactions were found to the extent of 35% and 9%, respectively, for monomers (89) and (88) in addition to the normal 1,2-addition mode. 

Para photocycloaddition of arenes to the benzene ring was first reported in 1971 by Wilzbach and Kaplan [7] as a minor process accompanying ortho and meta photocycloaddition. Since that time, relatively few cases of para photocycloaddition have been described. Para adducts were found as minor products from benzene with cyclobutene [8], ra- 3,4 - dimethyIcycIobu(ene [9], vinylene carbonate [10], 2,3-dihydropyran [11,12], and 1,3-dioxole [13,14] and from a,a,a-tri-fluorotoluene with vinylene carbonate [15], Intermolecular para photocycloadducts were major products from the irradiations of benzene and allene [16,17], benzene and cyclonona-1,2-diene [16,17], and from fluorobenzene and cyclopentene [18], Intramolecular para photocycloadducts were found as major products from the irradiations of phenethyl vinyl ether [19-21] (Scheme 3) and 2,3-dimethyl-6-phenylhex-2-ene [22], No detailed mechanistic investigations have been published. 

Benzo-l,3-dioxole (XXIII) is presumably nonaromatic, other than in its benzene ring. That there are ten 7t electrons does not make this species aromatic because the conjugation is interrupted [40, 41], much as the six-7t cycloheptatriene may enjoy homoaromatic stabilization but not aromatic stabilization, per se [42], Accordingly, we are confident that 2-benzimidazolinone (XXI) with its ten n electrons is aromatic. 

---