Comins reagent

Comins reagent is a reagent to introduce triflate moieties. 

In presence of NaUMDS the enolate of enone 9 is formed at -78 °C. Reaction of the enolate with Comins reagent (2-[7V,7V-bis(trifluoro-methylsulfonyl)amino]-5-chloropyridine) provides dienyl triflate 10. 

Aryl triflate 13 is obtained by reaction of silyl ether 12 with CsF, CS2CO3 and Comins reagent at room temperature. Under these reaction conditions the TIPS-ether is cleaved to provide the corresponding phenolate, which undergoes reaction with Comins reagent to give triflate 13 in a one-pot protocol. 

The addition of organolithiums to N.N-dimethylformamide (DMF) works well giving aldehydes in synthetically useful yields [27]. N-Melhylformanilide, Comins reagent, and N-formylpiperidine are possible alternatives. 

Reductive cleavage of the /tara-methoxyphenyl (PMP-) group released the primary alcohol and the compound was converted into the corresponding methyl glycoside upon reaction with methanol in the presence of PhsP.HBr [65]. Subsequently, the primary alcohol was replaced by iodine to yield 68 to pave the way for the introduction of the exomethylene functionality required for the key Perrier s carbocy-clization reaction. Carbocycle 70 was obtained after exposure of 5-enopyranoside 69 to Hg(OCOCp3)2 in acetone/acetate buffer and the subsequent p-elimination. The synthesis of the C-ring of the alkaloid was completed by 1,4-reduction and formation of the vinyl triflate 71 with the Comins reagent. 

The triflate (trifluoromethanesul-fonate) anion, CF3SO3, or TfO-is an excellent, non-basic leaving group. It Is often used as an oxygen-based alternative to halides, and metals will insert into the C-OSO2CF3 bond. Triflates, particularly aryl and vinyl triflates, can be made conveniently with Comins reagent. 

Organic Syntheses are a good source of ways to make reagents and ways to carry out reactions. Comins reagent is featured in Organic Syntheses, 1997, 74, 77. 

Related Reagents. 7V,yV-Phenyltrifluoromethanesulfonimide 2-[ N, 7V Bis(trifluoromethylsulfonyl)amino ]-5-chloropyridine (Comins Reagent). 

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