2- -l,3-dioxolane

Most of the synthetic approaches toward this ring system utilize N-amino pyridinium salts functionalized at the a-position with a carbonyl group. Thus, the amination of 2-(l,3-dioxolan-2-yl)pyridine with tosyl-hydroxylamine gave 78, whose reaction with urea in the presence of boron trifluoride-acetic acid gave 79, which gave the thermally unstable... 

A synthetic procedure 33 has been developed for the preparation of boronic acids with a protected aldehyde side chain, 2-(l,3-dioxolan-2-yl)ethyl, which is readily converted into boroOrn peptides similar to 30. Peptides containing boroLys were prepared by a series of reactions analogous to those used for the preparation of 30 except 4-bromobut-l-ene was used as starting material in place of 3-bromoprop-l -ene 36 ... 

Amino-3-hydroxy[3-13C]naphthalene, 88, has been obtained77 in seven steps starting with 2-(l,3-dioxolan-2-yl)-benzyl chloride and Na13CN (equation 40). The diazotation of the labelled amino compounds 88 followed by deprotonation provided [9a-13C]naphthol [2,3-d]-l,2,3-oxadiazole, 89 (equation 41). 

Methyl spiro[5-bromobicyclo[2.2.1]heptane 2,2 l,3-dioxolane]-7-carboxylate... 

Benzocy clobuten-< l-spiro-2)-l, 3-dioxolane 3-Methoxy-2-oxo- -E17f, 1333 (Oxo - O.O-acetal) Bicyclo 3.2.0 heptan 1,5-Dimeth-oxycarbonyl- IV/5a. 393 f. Bicyclo[4.1.0 heptan 7,7-Dimethoxy-carbonyl- E19b, 1049 (Carben + En)... 

Dioxolan-( 2-spiro-2>-benzocyclo-butene-(l-spiro-2)-l,3-dioxolane E17f, 1033 (Oxo -> O.O-acetal)... 

Benzocyclobiiten-< 1 -spiro-2>-l,3-dioxolan)-tricarbonyl- EI7f, 935/944 (Komplex-Synth.)... 

Cyclization of intermediates 165 and 166 occurred at the position with a larger superdelocalizability (see Section VI,A). PPP Calculations also support the angular forms. These compounds were not stable their color changed even in polar solvents. The salt from the reaction of 3,6-bis(bro-momethyl)catechol diacetate with 2-(l, 3-dioxolan-2-yl)pyridine was easily cyclized with 30% HBr in AcOH to afford the 6,7-dihydroxy derivative 164 (84%) (65JOC252). 

Homolytic benzylation of protonated quinoxaline yields 2-benzylquinoxaline, and with 1,3-dihctcrocycloalkancs, e.g. 1,3-dioxolane, 2-(l,3-dioxolan-4-yl)quinoxaline is formed. 2-Benzylquinoxaline is also the only product from the homolytic benzylation of quinoxaline with dibenzyl mercury. 

The reaction proceeds well in the presence of side chains with ether or acetal protecting groups, thus providing a convenient route to methylenecyclopropanes with hydroxy and oxo groups. The synthesis and subsequent hydrolysis of l,la,6,6a-tetrahydro-l-methylene-spiro[cyclopropa[c ]indene-6,2 -[l, 3]dioxolane] (10) provides an illustrative example. ... 

A few 6-methylenebicyclo[3.1.0]hex-2-enes have been prepared by dehydrochlorination of a 1-chloro-l-methylcyelopropane (see Section 5.2.2.1.1.1.) with potassium /ert-butoxide in dimethyl sulfoxide, combined with dehydrobromination to an alkenylcyclopropane (see Section 5.2.2.1.1.4.) in the same reaction step. Bromochloroacetals have been prepared from cyclo-pentenone acetals by chloromethylcyclopropanation followed by bromination. Thus, optically active truns-4, 5 -dimethyl-6-methylenespiro[bicyclo[3.1.0]hex-3-ene-2,2 -[l,3]dioxolane] (2) was obtained in 84% overall yield from the corresponding chloroacetal 1. ... 

Tricyclo 3.3.0.0 " octan-<3-spiro-2>-l,3-dioxolane Tricydo 4.3.2.0 lundeca-8,10-[Pg.3539]

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