One-pot synthesis of cyclic enecarbamates from lactam carbamates

An Efficient Transformation of Cyclic Ene-carbamates into .OMEGA.-(N-Formylamino)carboxylic Acids by Ruthenium Tetroxide Oxidation

“…19) We have previously tested the utility of the urethane type N-protecting groups, 9) benzyloxycarbonyl (Z), p-nitrobenzyloxycarbonyl (PNZ), trichloroethoxycarbonyl (Troc) and tert-butoxycarbonyl (Boc) groups for the RuO 4 oxidation of the cyclic amines, and found the following three points: (1) the Z group is decomposed by RuO 4 that produced a low yield of products, (2) the PNZ and Troc groups generally require a longer reaction until the starting materials disappear, and (3) the Boc group is stable, accelerates the oxidation, and affords the products in high yields. In addition, the Boc group can be easily removed from the Nprotected amines by common procedures.…”

“…The 3-H signal of the latter 10a was observed at d 5.31 as double-doublets in the lower field due to the deshielding effect of the carbonyl group at the C-2 position. The major compounds 9 were converted into the corresponding ene-carbamates (11) by the reported method, 19) which was reduction of the lactam carbamate with Super-Hydride, followed by in situ dehydration with trifluoroacetic anhydride (TFAA) and diisopropylethylamine (DIPEA). The 3-acetoxy (11a) and 3-silyloxy-1,2,3,4-tetrahydropyridines (11b) were obtained from the corresponding lactams (9) in 71 and 82% yields, respectively.…”

“…Starting Cyclic Ene-carbamates Unsubstituted N-protected cyclic enecarbamates (1a-3a, 19) 4a [20][21][22] ) were prepared by the reported method. New compounds, (5a, 23) 6a 19) ) were prepared from the corresponding lactams according to the procedure.…”

“…New compounds, (5a, 23) 6a 19) ) were prepared from the corresponding lactams according to the procedure. 4 Oxidation of N-Protected Cyclic Enecarbamates A solution of a substrate (12 mmol) to be oxidized in ethyl acetate (120 ml) was added to a mixture of RuO 2 · xhydrate (80 mg) and 10% NaIO 4 aqueous solution (320 ml).…”

A Unified Strategy Targeting the Thiodiketopiperazine Mycotoxins Exserohilone, Gliotoxin, the Epicoccins, the Epicorazines, Rostratin A and Aranotin

“…[ [26][27][28] The azabicyclic cyclobutanone 23 was isolated as a single diastereoisomer in good yield. [29] A proposed explanation of the obtained diastereoselectivity is shown in Scheme 5 (B).…”