Synthesis of Six- to Nine-Membered Ring Oximinoorthodithiolactones by Cyclization of NitroketeneS,S-Acetals in Trifluoromethanesulfonic Acid

Cyclization of Nitroacetamide Derivatives with a Tethered Phenyl Ring in Triflic Acid

“…26 The high stability of N-protonated oxime has also been reported in triflic acid. [6][7][8]10,11 Protonation of the heteroatoms thus affords stable polyprotonated species 16b insensitive to further electrophilic addition. Such a phenomenon has previously been proposed to explain the selective reactions on polyfunctionalized natural products in HF-SbF 5 .…”

“…The oxime configuration is consistent with the mechanism of an addition on a triple bond, as predicted 5 and in agreement with previously reported results. [6][7][8][9][10][11] The mechanism also explains why only the E-configured trication 16 was formed. The sequence is completed by the involvement of other transient superelectrophilic species as postulated previously for reactions in triflic acid.…”

“…6,7 They are able to react in situ either with anions Fin HF-SbF 5 6 or CF 3 SO 3 in triflic acid 8 or aromatic rings. [6][7][8][9][10][11] During the quenching of the acidic medium, they may either be trapped by MeSH or MeOH, 6 or form a very reactive nitrile oxide able to react with a phenyl ring by a cycloaddition process, to afford a conjugated cyclohexadiene (Scheme 2). 9 From a synthetic viewpoint, ethyl 2-nitroacetate (1) is a versatile synthon for the preparation of nitroacetamides in a one-step reaction with amines.…”

Oximes of Seven-Membered Heterocyclic Compounds Containing One Heteroatom

“…Hydrogenation of 4-nitro-2,3-dihydrobenzo[b]thiepine 1,1-dioxide (22) in the presence of 10% Pd/C in dioxane affords oxime 23 in 68% yield [36]. …”

Electrophilically Activated Nitroalkanes in Reactions With Carbon Based Nucleophiles

“…Low temperature quenching with methanol afforded cyclic oximes of isothiochromanones 11.9, and their higher cyclic homologs. It was shown that ring sizes 6-8 could be assembled very efficiently, but larger rings were produced in marginal yields (Scheme 11, Equation 2) (Coustard, 2001).…”