Chloro-l-butyne

A mixture of 0.10 mol of freshly distilled 3-methyl-3-chloro-l-butyne (see Chapter VIII-3, Exp. 5) and 170 ml of dry diethyl ether was cooled to -100°C and 0.10 mol of butyllithium in about 70 ml of hexane was added at this temperature in 10 min. Five minutes later 0.10 mol of dimethyl disulfide was introduced within 1 min with cooling betv/een -100 and -90°C. The cooling bath vjas subsequently removed and the temperature was allowed to rise. Above -25°C the clear light--brown solution became turbid and later a white precipitate was formed. When the temperature had reached lO C, the reaction mixture was hydrolyzed by addition of 200 ml of water. The organic layer and one ethereal extract were dried over potassium carbonate and subsequently concentrated in a water-pump vacuum (bath... 

A number of alternative multi-step procedures for the synthesis of a-tert-alkyl ketones are known, none of which possess wide generality. A previous synthesis of 2-tert-penty1cyclopentanone involved reaction of N-1-cyclopentenylpyrrol 1 dine with 3-chloro-3-methy1-l-butyne and reduction of the resulting acetylene (overall yield 46 ). However, all other enamines tested afford much lower yields. Cuprate addition to unsaturated ketones may be useful in certain cases. Other indirect methods have been briefly reviewed. ... 

Some synthetically important allenylmetallics, such as allenylzinc and allenylin-dium reagents, are prepared from allenylpalladium intermediates. These reactions are discussed in appropriate sections of this chapter. This section covers the reactions of allenylpalladium compounds without further transmetallation. Allenylpalladium complexes can be prepared from propargylic halides, acetates, carbonates, mesylates, alcohols and certain alkynes [83-87], The allenylpalladium compound prepared from 3-chloro-3-methyl-l-butyne has been isolated and characterized spectroscopically (Eq. 9.106) [83], It was found to couple with organozinc chlorides to produce homologated allenes quantitatively (Eq. 9.107). 

Chloro-3-methyl-l-butyne from the Corresponding Carbinol and Concentrated HCI... 

Presence of a certain type of functional groups in alkynes does not interfere with silylformylation. For example, the chlorine atom in 5-chloro-l-pentyne 44 and the cyano group in 5-cyano-l-pentyne 46 do not affect the silylformylation to give 45 and 47 respectively (Equations (10) and (11)). 4-Bromo-l-butyne and 6-bromo-l-hexyne also give the corresponding silylformylation products." ... 

Methyl 4-chloro-2-butynoate has been prepared in 54% yield by treatment of 4-chloro-2-butynoic acid with 10% sulfuric acid in methanol. 4-Chloro-2-butynoic (chlorotetrolic) acid has been prepared in 40% yield by chromic acid oxidation of 4-chloro-2-butyn-l-ol (the latter obtained 1n 45% yield by the reaction of 2-butyne-l, 4-diol with thlonyl chloride) or in 85% yield by treatment of the lithium derivative of propargyl chloride with carbon... 

Formylation of 5,7-dihydroxy -( -propyl)-coumarin (1) provided on 8-formy-lated product (26). Treatment of the compound 26 with 3-chloro-3-methyl-l-butyne to introduce regioselectively the chromene 27 because the phenolic hydroxyl group at the C position was less accessible for formylated substitution because of a presumed hydrogen-bonding interaction. To construct the enantiomerically pure rra i-2,3-dimethyl chroman-4-ol system, Deshpande et al." ° used organoborone... 

Chloro-3-methyl-l-butyne, 916 2-Chloro-2-methyl-3-butyne, 916 2-Chloro-2-methylcyciohexanoae, 609,1128 N-2-Chloromethyl-0,N-dimethylhydroxyl-amine, 1078... 

A one-step synthesis of this alkaloid is consequent upon the reaction of thallous salts of nonchelated j8-diketones with alkyl halides. In the present instance the thallous salt of 4-hydroxyquinolone (93) reacted with 3-chloro-3-methyl-l-butyne to generate flindersine (94) in 28% yield 111). 

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