From fluoroaldehydes

CO + HF) from pentafluorophenol (CHO + F) from fluoroaldehydes Aromatic sulfoxides... 

That an aminal is a necessary intermediate was first questioned by Herr and Heyl (2). They found that by using a slight excess of amine the yield of the enamine from two of the steroidal aldehydes studied was 84%. Also, the -fluorocnamines discussed earlier are formed in 60-90% yield from equimolar amounts of the 8-fluoroaldehyde and secondary cyclic amine (27). However, neither of these studies was specifically designed to show whether or not aminals were intermediates. 

Epoxidation also proceeds (Eq. 141) under mild conditions and with high stereoselectivity (95 5 erythro threo) despite the deactivating effect of the fluorine atom [361]. At a higher oxidation level, the Lausanne group described chemistry of a metallated azomethine derived from a,/Lunsaturated-a-fluoroaldehydes [362]. Highly flexible chemistry allowed alkylation at nitrogen, or at the (fluori-nated) -position, or at the -position (Fig. 8). 

From a non-c ohydrate precursor, Davis and Qi achieved the asymmetric synthesis of 2-deoxy-2-fluoro- iylo-D-pyranose (9) (Figure 7) and 2-deoxy-2-fluoro-lyxo-L-pyranose (13). TTie key reaction was the highly diastereoselective fluorination of a chiral enolate using the electrophilic fluorinating agent, N-fluoro(benzenesulfonimide) (NFSi). In another study by Davis (14), the use of a chiral oxazolidinone adjuvant and fluorination with NFSi led to the chiral fluorohydrin 10 (>97% ee), which was oxidized by the Dess-Martin periodinane procedure to the non-racemic a- fluoroaldehyde 11 (94% ee). Conversion of 11 in four steps provided l,2,3-tri-0-acetyl-4-deoxy-4-fluoro-D-arabinopyranose (12) as a 1 1 mixture of anomers which could not be separated by flash chromatography. 

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