3- methylbenzene-, lithium

The lithium salts of the a-sulfinyl carbanions have been alkylated by alkylating reagents other than iodomethane. For example, alkylation of ( + )-l-[( )-ethylsulfinyl]-4-methylbenzene with lithium bromoacetate in the presence of lithium diisopropylamide gave (5)-3-[(2 )-4-methylphen-ylsulfinyl]butanoic (7) acid as the major product (d.r. 8 2) which was isolated as a pure solid in 58% yield55. 

FLUORO-2-METHYLBENZENE (95-52-3) Forms explosive mixture with air (flash point 55°F/13°C). Reacts with atmospheric moisture, water, steam, forming hydrogen fluoride and benzoic acid. Violent reaction with oxidizers, lithium. Attacks metals in the presence of moisture. 

Both these compounds, 143a and b, needed to investigate the mechanism of biosynthesis of the plant growth hormone ethylene, have been prepared according to the reaction scheme in equation 6599. 144a and b have been prepared by reduction of unlabelled or deuterated ethyl bromoacetate with lithium aluminium deuteride-anhydrous aluminium chloride. Subsequently, 143a and 143b have been synthesized with 4-methylbenzene-... 

STRATEGY AND ANSWER In (1), we must oxidize methylbenzene to benzoic acid. To do this we use hot potassium permanganate in a basic solution followed by an acidic workup (see Section 15.13C). For (2), we must convert a carboxylic acid to an acid chloride. For this transformation we use thionyl chloride or phosphorus pentachloride (see Section 15.7). For (3), we must reduce an acid chloride to an aldehyde. For this we use lithium tri-rerf-butoxyaluminum hydride (see above). 

CHAiUNCt Identify compounds A, B, and C from the following information and explain the chemistry that is taking place. Reaction of the alcohol shown below with 4-methylbenzene-sulfonyl chloride in pyridine produced A (C15H20O3S). Reaction of A with lithium diisopropylamide (LDA, Section 7-8) produces a single product, B (C8H12), which displays in its H NMR a two-proton multiplet at about 5 = 5.6 ppm. If, however, compound A is treated with Nal before the reaction with LDA, two products are formed B and an isomer, C, whose NMR shows a multiplet at 5 = 5.2 ppm that integrates as only one proton. 

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