3663-79-4Relevant articles and documents
A short entry to enantiopure 2-substituted 1,4-benzodioxanes by efficient resolution methods
Bolchi, Cristiano,Fumagalli, Laura,Moroni, Barbara,Pallavicini, Marco,Valoti, Ermanno
, p. 3779 - 3785 (2003)
(R)-1,4-Benzodioxane-2-carboxilic acid (R)-1 was obtained by resolution of the racemic acid 1 with stoichiometric or nonstoichiometric (+)- dehydroabietylamine (+)-2 in high chemical yield and enantiomeric excess. (S)-1 was isolated from the mother liquors of the crystallisation of (R)-1·(+)-2 and its enantiomeric excess maximised by recrystallisation procedures involving a precipitation under kinetic control or, alternatively, by conversion into the methyl ester followed by a single crystallisation. The different mechanisms of the two S enrichments is well explained by the binary phase diagrams of the acid and of the ester, which show that the former is a racemic compound, whereas the latter a conglomerate. The DSC analyses were extended to 2-hydroxymethyl- and 2-mesyloxymethyl-1,4-benzodioxane, establishing that the alcohol forms a racemic compound, while its mesyl ester a conglomerate. On the basis of these results, different resolution strategies can be designed to obtain useful homochiral 2-substituted 1,4-benzodioxanes coupling the resolution of 1 via diastereomeric salt formation with the enantiomeric enrichments by recrystallisations, preferably of its conglomerate forming derivatives.
From 2-aminomethyl-1,4-benzodioxane enantiomers to unichiral 2-cyano- and 2-carbonyl-substituted benzodioxanes via dichloroamine
Bolchi, Cristiano,Valoti, Ermanno,Straniero, Valentina,Ruggeri, Paola,Pallavicini, Marco
, p. 6732 - 6737 (2014/08/05)
2-Substituted 1,4-benzodioxanes, such as 2-cyano-, 2-methoxycarbonyl-, 2-aminocarbonyl-, and 2-formyl-1,4-benzodioxane, are key synthons that for the most part are never described as enantiomers or are inadequately characterized for enantiomeric purity. They were prepared by quantitative N,N-dichlorination of (R)- and (S)-2-aminomethyl-1,4-benzodioxane and successive functional group conversions in high yields without any racemization of the stereogenic benzodioxane C(2).
Chemoenzymatic synthesis of piperoxan, prosympal, dibozane, and doxazosin
Rouf, Abdul,Gupta, Pankaj,Aga, Mushtaq A.,Kumar, Brijesh,Chaubey, Asha,Parshad, Rajinder,Taneja, Subhash C.
supporting information, p. 1615 - 1623 (2013/02/22)
The synthesis of both enantiomers of 1,4-benzodioxan-2-carboxylic acid 1, a key synthetic intermediate for the therapeutic agents piperoxan, prosympal, dibozane, and doxazosin was achieved with good yields and high enantioselectivities via the Arthrobacter sp. lipase catalyzed kinetic resolution of ester (±)-17a. The influence of the co-solvents and the immobilization of the lipase upon kinetic resolution demonstrated that immobilized whole cells, in the presence of n-butanol as a co-solvent, resulted in the optimal resolution of the substrate (ee ～99%, E = 535) at 258 mmol (50 g/L) substrate concentration.
