- One-pot, three-step preparation of alkyl and aryl alkylcarbamates from S-methyl N-alkylthiocarbamates
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A general procedure for the synthesis of alkyl and aryl alkylcarbamates starting from the corresponding 5-methyl N-alkylthiocarbamates is described. This procedure consists of three steps that are carried out in a one-pot fashion, without isolating the intermediate N-alkylcarbamoyl chlorides or alkyl isocyanates. All the target products were obtained in high yields (16 examples, average yield 91%). To be noted is the recovery of a co-product of industrial interest, dimethyl disulfide, in a half mole amount for each mole of thiocarbamate, with complete exploitation of the reagent. The alkyl isocyanates, if required, can also be isolated in high yields. Georg Thieme Verlag Stuttgart.
- Artuso, Emma,Degani, Iacopo,Fochi, Rita,Magistris, Claudio
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experimental part
p. 1612 - 1618
(2009/04/03)
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- An easy and efficient one-step procedure for the preparation of alkyl and aryl alkylcarbamates from S-methyl N-alkylthiocarbamates
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A general, one-step procedure for the synthesis of alkyl and aryl alkylcarbamates, by the direct reaction of S-methyl N-alkylthiocarbamates with alcohols or phenols in toluene at reflux in the presence of triethylamine, is reported. All the target products were obtained in high yield (15 examples, average yield 94%) and very high purity (>99.2%). The recovery of a co-product of industrial interest, methanethiol, in an amount of one mole for each mole of thiocarbamate, with complete exploitation of the reagent, should also be noted. Georg Thieme Verlag Stuttgart.
- Degani, Iacopo,Fochi, Rita,Magistris, Claudio
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experimental part
p. 2919 - 2924
(2009/04/06)
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- Base catalyzed cyclization of N-aryl and N-alkyl-O-propargyl carbamates to 4-alkylidene-2-oxazolidinones
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The base catalyzed cyclization of N-aryl and N-alkyl-O-propargyl carbamates is studied in detail. The effect of various bases and solvents on the efficacy of this cyclization reaction is analyzed and a new base-solvent system (LiOH in DMF) for effective cyclization of these carbamates is reported. A number of differentially substituted O-propargyl carbamates were cyclized to the corresponding 2-oxazolidinones under these conditions. The reaction conditions reported here are mild and no side reactions were observed in any of the substrates studied. A propargyl carbonate group was unaffected during the course of the cyclization of the O-propargyl carbamate group. The propargyl carbamates were prepared from the corresponding alkyl or aryl amines and the corresponding propargyl chloroformate, resulting in oxazolidinones diversely substituted at the nitrogen atom. N-Aryl-O-propargyl carbamates cyclized readily to the corresponding oxazolidinones with LiOH in DMF, whereas N-alkyl-O-propargyl carbamates reacted slowly under the same conditions. O-Propargyl carbamates substituted at the 1-position tend to cyclize faster whereas those substituted at 3-position cyclize considerably slower than the unsubstituted carbamates.
- Ramesh, Ramapanicker,Chandrasekaran, Yogesh,Megha, Rajendran,Chandrasekaran, Srinivasan
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p. 9153 - 9162
(2008/02/10)
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- Concomitant Desulfurization and Transesterification of Alkyl Thionocarbamates
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Alkyl carbamate (such as 1) reacts with triphosgene at the nitrogen atom, whereas the analogous thionocarbamates (5) react at the sulfur. Subsequent treatment with various phenols or alcohols leads to the corresponding aryl carbamates or alkyl carbamates
- Joshi, Uday M.,Patkar, Laxmikant N.,Rajappa, Srinivasachari
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- New polymer-supported allyloxycarbonyl (Alloc) and propargyloxycarbonyl (Proc) amino-protecting reagents
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New polymer-supported reagents, Alloc-P-OSu and Proc-P-OSu, have been prepared from a polymeric N-hydroxysuccinimide (P-HOSu), and used as solid-supported reagents for the allyloxycarbonyl (Alloc) and propargyloxycarbonyl (Proc) protection of the amino group. These new polymeric reagents are safe and stable, the residual P-HOSu generated after the protection reaction can be easily separated by simple filtration and reused.
- Chinchilla, Rafael,Dodsworth, David J.,Nájera, Carmen,Soriano, José M.
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p. 809 - 812
(2007/10/03)
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- Process for preparation of halopropargyl carbamates
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A process for preparing halopropargyl carbamates which avoids using phosgene as a starting material. N-butyl iodopropargyl carbamate is an especially preferred product of the novel process.
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