2.3- dihydro-l,4-benzodioxins

Intramolecular cyclization can yield fluorinated phenoxazines by a Smiles rearrangement (86IZV1855) and 2,3-dihydro-l,4-benzodioxins by a base-induced reaction [81JFC(18)483]. 

CN l-(4-amino-6,7-dimethoxy-2-quinazolinyl)-4-[(2,3-dihydro-l,4-benzodioxin-2-yl)carbonyl]piperazine hydrochloride... 

RN 2165-19-7 MF CioH.jNjO MW 207.23 CN [(2,3-dihydro-l, 4-benzodioxin-2-yl)methyl]guanidine... 

MDL 73005 = 8,2 (2,3-dihydro-l,4-benzodioxin-2yl) methylamino-ethyl-8-azaspirol (4,5) decan-7,9-dione NAN 190 = l-(2-methoxyphenyl) 4-(4(2-phthalimido)entyl-piperazine)... 

Most partially saturated ring systems, 2,3-dihydro-l,4-dioxin 10 (sometimes named as 1,4-dioxene), 2,3-dihydro-1,4-dithiin 11, 2,3-dihydro-l,4-oxathiin 12, 2,3-dihydro-l,4-benzodioxin or 1,4-benzodioxane 13, 2,3-dihydro-l,4-benzodithiin 14, and 2,3-dihydro-l,4-benzoxathiin 15 are well investigated. Ring numbering for compounds 10-12 is followed as shown, independently of the presence of substituents. 

Cyclizations of o-(a -haloalk oxy)phenols have been widely studied and were used to afford an expedient synthesis of 5-alkyl-2,3-dihydro-l,4-benzodioxins <2004SC2487>. This approach via a nucleophilic substitution was used for the synthesis of 8-substituted-2-hydroxymethyl-l,4-benzodioxane derivatives 164 in an enantiopure form. Use of CsF instead of more basic conditions allowed higher yields and enantiomeric excess (Equation 28) <2001ASC95>. Dry tetrabutylammonium fluoride (TBAF) in THF was required and was basic enough to initiate an intramolecular Sn substitution from the protected phenol 165 to the fluoro-l,4-benzodioxane 166 <1996T6187>. 

Finally, l,4-benzodioxin-2-carboxylic esters or carboxamides react with nucleophilic amines to give access to 3-hydroxy-2,3-dihydro-l,4-benzodioxin-2-carboxamides and 3-aminomethylene-l,4-benzodioxin-2(777)-one 263 <2003T1227>. 

Perfluorobenzene and ethylene glycol can react to give, according to the conditions used, 2-(pentafluorophenoxy)ethanol (12),89 l,2,4,5-tetrafluoro-3,6-bis(2-hydroxyethoxy)benzene (14),90 and 5,6,7,8-tetrafluoro-2,3-dihydro-l,4-benzodioxin (13).89... 

The base 2-guanidinemethyl-2,3-dihydro-l,4-benzodioxine may be obtained by reaction of di(2-guanidinomethyl-l,4-benzodioxane)sulfate with, for example, sodium hydroxide. 

To solution of 2-hydroxymethyl-2,3-dihydro-l,4-benzodioxine thionylchloride was added to give 2-chlormethyl-2,3-dihydro-l,4-benzodioxine. 

Conformations. Conformational analyses have been reported for 2-methyl-, 2,3-dimethyl-, 2,5-dimethyl-, and 2,6-dimethylpyrazine 1070 for 1,4-dihydropy-razine 1459 for 1-phenyl-, 1 -io-, m-, or p-monosubstituted phenyl)-, l-(2,3-dihydro-l,4-benzodioxin-5-yl)- (241), and l-(pyridin-4-yl)piperazine 490 and for 2-(piperazin-l-ylpyrimidine (242).490 Alkyl-alkylidene tautomerism has been discussed theoretically.932... 

An enantioselective aryloxylation of aldehydes is based on their prior conversion to an enamine through reaction with a chiral secondary amine catalyst. A subsequent inverse HDA reaction with o-quinones leads to 3-alkyl-2-hydroxy-l,4-benzodioxins with ee ca. 80% (Scheme 47). Manipulation allows the synthesis of (S)-2-alkyl-2,3-dihydro-l,4-benzodioxins <07TL1605>. In like manner, racemic nitidanin, which possesses antimalarial properties, has been synthesised through a regioselective cycloaddition of an o-quinone with a protected 3-arylpropen-l-ol <07TL771>. 

The reaction between ethylenediamine and 2-carboxy-2,3-dihydro-l,4-benzodioxin yielded four detectable products. The two major products were shown to be the dioxole (102) (45%) and catechol (29%). An analytical investigation of this process has revealed that, prior to the final distillation, the reaction gave a major product (103) which was different from the four mentioned above <84JHC77>. 

Methoxy and 6-tetrahydropyranyloxy-2,3-dihydro-l,4-benzodioxin can be lithiated by butyl-lithium in tetrahydrofuran, at — 50 °C, to give intermediate lithio derivatives which react with various electrophiles to afford, after hydrolysis, 5-substituted-6-methoxy and 6-hydroxy-2,3-dihydro-l,4-... 

Dihydro-l,4-benzodioxin 60.2 252 Tubular flow reactor 1994SCH/ARE... 

Dihydro-l,4-benzodioxines 139 and 140 are prepared by the reaction of propargyl carbonates 136 with catechol (137) by attacking either terminus of the TT-allylpalladium intermediate 138. 

S (Z)]]-7-[(2-amino-2-carboxyethyl)thio]-2-[[(2,2-dimethylcyclopropyl)carbonyl]amino]-2-heptanoic acid cjs-4-amino-5-chloro-N-[l-[3-(p-fluorophenoxy)propyl]-3-methoxy-4-piperidinyl]-o-anisamide cis-4-amino-5-chloro-N-[l-[3-(4-fluorophenoxy)propyl]-3-methoxy-4-piperidinyl]-2-methoxybenz amide [l-amino-3-[[[2-[(diaminomethylene)amino]-4-thiazolyljmethyl] thio]propylidene]sulfamide 2-amino- l,9-dihydro-9-[(2-hydroxyethoxy)methyl]-6H-purin-6-one l-(4-amino-6,7-dimethoxy-2-quinazolinyl)-4-[(2,3-dihydro-l,4-benzodioxin-2-yl)carbonyl]piperazine... 

Scheme 4.23 Cu-catalyzed domino ring opening/coupling cyclization of o-iodophenols with epoxides Synthesis of 2,3-dihydro-l,4-benzodioxins.

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