518038-93-2

Upstream product

• 32315-10-9 bis(trichloromethyl) carbonate 
• 1504-58-1 3-Phenyl-2-propyn-1-ol 

Downstream Products

• 929563-04-2 3-phenylprop-2-yn-1-yl phenylcarbamate 
• 951009-97-5 C₁₇H₁₅NO₂ 
• 1419208-83-5 3-phenylprop-2-ynyl methylphenylcarbamate 
• 1338920-78-7 C₁₈H₁₃NO₃ 

Relevant academic research and scientific papers

Preparation method of alicyclic and aromatic-aliphatic chloroformate

The invention belongs to the technical field of fine chemistry, and in particular relates to a preparation method of alicyclic and aromatic-aliphatic chloroformate. The preparation method is characterized in that alicyclic alcohol chloroformate or aromatic-aliphatic alcohol chloroformate is obtained by taking alicyclic alcohol or aromatic-aliphatic alcohol and bis(trichlormethyl)carbonate as raw materials, taking organic base as a catalyst and reacting in an organic solvent under certain reaction temperature and certain reaction time, wherein molar ratio among the alicyclic alcohol or the aromatic-aliphatic alcohol, the bis(trichlormethyl)carbonate and the organic base is 1 to (0.4 to 1) to (1.2 to 3); experiment time and experiment temperature are different in two stages, in the first stage, the reaction temperature is -10 to 0 DEG C, and the reaction time is 2 to 5 hours; in the second stage, the reaction temperature is 0 to 25 DEG C, and the reaction time is 7 to 13 hours; a mass ratio between the organic solvent and the alicyclic alcohol or the aromatic-aliphatic alcohol is (10 to 25) to 1; residue in a reaction system is effectively treated, and reaction waste is also recycled and utilized. The preparation method disclosed by the invention has the characteristics of stable reaction, high reaction yield and product purity, environment protection of a reaction process, low production cost, less emission of three wastes, simpleness in preparation technology and easiness in industrialization.

Lithium choreography: Intramolecular arylations of carbamate-stabilised carbanions and their mechanisms probed by in situ IR spectroscopy and DFT calculations

Deprotonation of O-allyl, O-propargyl or O-benzyl carbamates in the presence of a lithium counterion leads to carbamate-stabilised organolithium compounds that may be quenched with electrophiles. We now report that when the allylic, propargylic or benzylic carbamate bears an N-aryl substituent, an aryl migration takes place, leading to stereochemical inversion and C-arylation of the carbamate α to oxygen. The aryl migration is an intramolecular S NAr reaction, despite the lack of anion-stabilising aryl substituents. Our in situ IR studies reveal a number of intermediates along the rearrangement pathway, including a "pre-lithiation complex," the deprotonated carbamate, the rearranged anion, and the final arylated carbamate. No evidence was obtained for a dearomatised intermediate during the aryl migration. DFT calculations predict that during the reaction the solvated Li cation moves from the carbanion centre, thus freeing its lone pair for nucleophilic attack on the remote phenyl ring. This charge separation leads to several alternative conformations. The one having Li+ bound to the carbamate oxygen gives rise to the lowest-energy transition structure, and also leads to inversion of the configuration. In agreement with the IR studies, the DFT calculations fail to locate a dearomatised intermediate. Dancing to lithium's tune: In situ IR spectroscopy and DFT calculations allow the detailed pathways of aryl migrations taking place in lithiated carbamates to be characterised (see scheme).

Base catalyzed cyclization of N-aryl and N-alkyl-O-propargyl carbamates to 4-alkylidene-2-oxazolidinones

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.