Propargylic chloride, dicarbonylation

Dicarbonylation occurs mainly by the carbonylation of propargylic halides and alcohols carried out under a high pressure of carbon monoxide. The carbonylation of propargyl bromide (51) at 20 atm affords 2,3-butadienoate (52) as described in Section 11.3.2.2. On the other hand, carbonylation of propargyl chloride (77) in methanol at room temperature under high pressure (100 atm) catalyzed by PdClj or Pd/charcoal afforded dimethyl itaconate (79). The primary product seems to be 2,3-butadienoate (78), which is carbonylated further (Scheme 11-23) [10,11]. As supporting evidence, formation of diethyl itaconate (81) in 64% yield by the carbonylation of ethyl 2,3-butadienoate (80) at room temperature under high pressure was confiimed. 

The formation of an allenyl ketone as the sole product can be achieved by using an excess (2 equiv.) of propargyl bromide (entries 3—6, Table 5.9). Use of an increased amount (3 equiv.) of the acylzirconocene chloride in the reaction with propargyl bromide and/or tosylate yields a significant amount of a 1,4-dicarbonyl compound derived from Michael-type addition of the acylzirconocene chloride to the initially formed allenyl ketone (entry 2, Table 5.9). The Michael-type addition of acylzirconocene chlorides to allenyl ketones under Cu(I)-catalyzed conditions has been confirmed by an independent experiment (Scheme 5.31). 

Schulte and coworkers (62AP801) have prepared a number of 3-propargyl-4-hydroxy-2-pyrone derivatives (210) by condensation of /3-dicarbonyl compounds (208) with propargyl-malonyl chloride (209). On heating (210) with zinc carbonate, ring closure took place to give the corresponding furo[3,2-c]pyrone derivatives (211 Scheme 40). 

The coupling reaction of a-keto esters with allyl, propargyl, and allenyl halides using indium metal in aqueous solvents affords a-hydroxy-y,<5-unsaturated esters (Equation (28)).197,198 1,3-Dicarbonyl compounds undergo efficient carbonyl allylation reactions in an aqueous medium through a Barbier-type reaction (Equation (29)). The reaction is general and a variety of 1,3-dicarbonyls has been alkylated using allyl bromide or allyl chloride in conjunction with indium.199... 

A ruthenium-catalyzed three-component reaction between propargylic alcohols, 1,3-dicarbonyl compounds, and primary amines leading to fully substituted pyrroles was developed <07CEJ9973>. Cyclohexa[a]pyrroles ( azabicyclo[4.3.0] systems ) were formed by a three-component sequence involving allenic ketones, primary amines, and acryloyl chloride <07SL431>. An oxidative dimerization sequence involving arylpyruvates in the presence of ammonia was the key step in an approach to the pyrrole natural product, lukianol A <07S608>. 

An analogous propargylation/amination/cycloisomerization sequence with pyrrole formation was established for propargylic alcohols 92, 1,3-dicarbonyl compounds and primary amines with catalysis of In(III) chloride [128]. 

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