Labeled furans, synthesis

Petrick K, McLachlan MS (1994), Organohalogen Compounds 19 93-96. A rapid synthesis of 13C-labelled internal standards for the analysis of brominated dibenzo-p-dioxins and dibenzo-furans and mixed brominated/chlorinated dibenzo-p-dioxins , Eds. University of Kyoto, Japan... 

Labelled tropanes, particularly ring radiolabelled cocaines, have been described. A technical synthesis of some tropane derivatives from agricultural waste via 2,5-dimethoxyfuran, followed by hydrogenation to 2,5-dimethoxytetrahydro-furan, has been elaborated. 

Furoquinoline alkaloids specifically labeled with 14C in the furan ring were required for biosynthetic studies (see Section VII of this chapter), and since existing routes produced low yields, Grundon and co-workers (195, 196) developed a more efficient synthesis from 4-methoxy-3-prenyl-2-quinolones 244-246. These compounds had previously been prepared from aromatic amines and substituted malonates, but direct allylation is more suitable for the preparation of labeled compounds, employing, for example, [14C]-3,3-dimethylallyl bromide. It was found that reaction of... 

The enantioselective synthesis of (-i-)-shikimic acid and (-i-)-5-ep/-shikimic acid by an asymmetric Diels-Alder reaction of (5)-a-sulfmylacrylates with furan was reported. In the Diels-Alder reaction between acryloyloxazolidinone and furan catalyzed by a chiral cationic Cu(II) complex a high enantioselectivity was observed <97TL57>. The synthesis of ubiquinones-3 specifically labelled with C at the C(5)- or C(6)-positions starting with 2,5-bis(trimethylsilyloxy)-3-methylfuran and (2- C)-2-bromo-l,2-dichloroethene was reported <97T2505>. Diels-Alder reactions of 5-triisopropylsilyl-2-vinylfuran and 2-triethylsilyl-4-vinylfuran with acetylenic and olefinic dienophiles occur with high site specificity in the extraannular mode to produce trialkylsilylbenzofuran derivatives <97H(45)1795>. 

---