McMurray coupling

Our second attempt at using the microwave to accelerate reaction rates was on a library of indoles generated by a McMurray coupling reaction. Heating the reaction mixture at 80°C for 8 h produced poor yields of the desired product (entry 1, Table 8.3). However, when the microwave was utilized the isolated yield was raised to 79% and the reaction was completed in only 5 min. This reaction acceleration allowed for the production of a 300-membered library, which produced compounds of high quality in a significantly reduced time. 

This flexible synthesis depends on the reductive cychsation of ortfto-acyl-aniMes with low-valent titanium - the conditions used for the McMurray coupling of ketones. In the example below, the cyclisation precursor was built up via the acylation of 2-tri-n-butylstannylthiazole. ... 

Joining two halves directly. McMurray coupling of ketones with zero-valent titanium is a straightforward way (when it works) of converting ketones to alkenes it did not work for 17. 

The McMurray coupling of ketones has proved to be a very useful method of carbocyclic synthesis and this has now been extended to the synthesis of sulphur heterocycles. Thus treatment of the diketo-sulphides (97) with low-valent Ti (from TiCl and Zn) at low... 

Alternatively, McMurray coupling of a,a -thiobis(aryl)ketones leads to 2,5-dihydroihiophenes, using comparable conditions, but at a higher temperature [105, 106]. The 2,5-dihydrothiophenes can easily be dehydrogenated to the 3,4-diarylthiophenes, with DDQ [105] or copper(II) bromide [107]. 

McMurray [151] has described the acid-assisted cleavage of the N]-C4 bond in trans 4-hydroxyphenyl p-lactams. The ring opening reaction may proceed with concomitant reduction or formation of carbon-carbon coupling products, as a function of the reagent employed. For instance, Scheme 60, treatment of 196 with 4 equivalents of triethylsilane in neat trifluoroacetic acid led to compound 197. On the contrary, treatment with anisole in trifluoroacetic acid led to compound 198. Unfortunately, no data are provided by authors regarding process yield or final diastereomeric ratio. 

McMurray, J. S., Lewis, C. A., and Obeyesekere, N. U. (1994) Influence of solid support, solvent and coupling reagent in the head-to-tail cyclisation of resin-bound peptides. Pept. Res. 7, 195-206. 

JS McMurray, CA Lewis, NU Obeyesekere. The influence of solid support, solvent, and coupling reagent on the head-to-tail cyclization of resin bound peptides. Peptide Res 7 195-206, 1994. 

JA7582>. The reductive coupling of (3) by the McMurray reaction gave the substituted phosphepin (4) as a distillable oil that crystallized in 8-10% yield after purification by HPLC <84AG(E)894>. 

McMurray s reductive coupling of ketones has been used in a transannular fashion to furnish the tricyclo[6.3.0.0 > ]undecene (79), which is the basic ring system of the capnellanes, hirsutanes, and coriolins. Geise et al. have studied the reductive coupling of ketones, using titanium tetrachloride or trichloride as a reducing agent, and have optimized the conditions. Other studies have shown... 

The number of illustrations of the use of McMurray s reagent (TiCl3-LiAlH4) in the reductive coupling of carbonyl compounds to alkenes has burgeoned in the... 

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