Towards cyclic, conformationally constrained, fluorine-containing β-amino acid derivatives from d-glucose

Recent Advances in Nucleophilic Fluorination Reactions of Organic Compounds­ Using Deoxofluor and DAST

“…Deoxofluor (1) and DAST (2) have been utilized for such molecules (Table 2). 6, [18][19][20][21][22][23][24][25][26][27][28][29]…”

(Phenylthio)trimethylsilane

“…Simultaneous addition of ZnI 2 and PhSTMS was found to be important in order to avoid substitution of 6-O-acyl group by thiophenyl nucleophile. 24 Acetal modification using only catalytic amounts of Lewis acid (zinc(II) chloride) has been reported (eq 11 In cases when reaction proceeds through oxonium 29, 30 or iminium ion 31 intermediates with the methoxy as a leaving group, phenylthioacetal installation is generally carried out using PhSTMS/ZnI 2 /Bu 4 NI combination of reagents. Phenylthioacetal can be subsequently reduced with lithium di-t-butylbiphenylide (LiDBB) to give an organometallic compound, which in turn can be coupled with various electrophiles (eq 13 ).…”

“…The aldol reaction of the lithium enolate with aldehyde takes place from the bottom face, anti to the phenylsulfenyl group in the thermodynamic enolate conformation (eq 30). 60 (30) …”

Cross-Metathesis Reactions as an Efficient Tool in the Synthesis of Fluorinated Cyclic β-Amino Acids

“…So far, however, most of the reported examples focus on the synthesis of acyclic compounds . In fact, the only examples of cyclic derivatives that have been described to date are a racemic difluorinated analogue of cispentacin and a fluoropyranose containing a β 2,2 -amino acid unit . The lack of a general synthetic strategy, coupled with our current interest in obtaining various types of fluorinated nitrogen-containing heterocycles with the aid of metathesis reactions, led us to embark on the development of two complementary synthetic routes for the preparation of five- to seven-membered difluoro β 2,3 -amino acid derivatives with a CF 2 group next to the amino group.…”