2- Methyl-3-butyn reaction

METHYL BUTYN-3-OL (115-19-5) Forms explosive mixture with air (flash point <70°F/21°C). Violent reaction with strong oxidizers. Reacts violently with aliphatic amines, alkalis, ammonium persulfate, boranes, bromine dioxide, isocyanates, nitric acid, perchlorates, permanganates, peroxides, sodium peroxide, sulfuric acid, uranium fluoride,... 

It was found later that ET-NBE could be replaced by any monosubstituted acetylene, e.g. the much cheaper phenylacetylene, as long as the acetylene was present in approximately equimolar amounts, relative to the catalyst. Table 2 lists some other acetylenes, which were tested. It was also noted that the curing behaviour was influenced by the type of acetylene. For example the curing with 3-hydroxy-3-methyl-butyne led to a slower reaction which is less exothermic and could therefore be used for the curing of large objects. 

A solution of 0.60 mol of ethyllithium (note 1) in about 400 ml of diethyl ether (see Chapter II, Exp. 1) was added in 30 min to a mixture of 0.25 mol of 1,4-diethoxy-2-butyne (see Chapter VIII-6, Exp. 8) and 100 ml of dry diethyl ether. The temperature of the reaction mixture was kept between -40 and -45°C. Fifteen minutes after the addition had been completed, 0.5 mol of methyl iodide was added at -40 C, then 100 ml of dry HMPT (for the purification see ref. 1) were added dropwise in 15 min while keeping the temperature at about -40°C. Thirty minutes after this addition the cooling bath was removed, the temperature was allowed to rise and stirring was continued for 3 h. The mixture was... 

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... 

The carbonylation of 2-methyl-3-butyn-2-oI (50) in benzene gives teraconic anhydride (51). Fulgide (53) (a dimethylenesuccinic anhydride derivative), which is a photochromic compound, can be prepared by the carbonylation of 2,5-dimethyl-3-hexyne-2,5-diol (52)[21], The reaction proceeds under milder conditions when PdlOAc) is used as a catalyst in the presence of iodine [23],... 

Methylbutynol. 2-Methyl-3-butyn-2-ol [115-19-5] prepared by ethynylation of acetone, is the simplest of the tertiary ethynols, and serves as a prototype to illustrate their versatile reactions. There are three reactive sites, ie, hydroxyl group, triple bond, and acetylenic hydrogen. Although the triple bonds and acetylenic hydrogens behave similarly in methylbutynol and in propargyl alcohol, the reactivity of the hydroxyl groups is very different. 

Fluoride ion attacks the sulfur atom in 2,3-diphenylthiirene 1,1-dioxide to give ck-1,2-diphenylethylenesulfonyl fluoride (23%) and diphenylacetylene (35%). Bromide or iodide ion does not react (80JOC2604). Treatment of S-alkylthiirenium salts with chloride ion gives products of carbon attack, but the possibility of sulfur attack followed by addition of the sulfenyl chloride so produced to the alkyne has not been excluded (79MI50600). In fact the methanesulfenyl chloride formed from l-methyl-2,3-di- -butylthiirenium tetrafluoroborate has been trapped by reaction with 2-butyne. A sulfurane intermediate may be indicated by NMR experiments in liquid sulfur dioxide. 

It should be noted that a considerable acceleration of the reaction for low-reactive 4-iodopyrazoles is observed for substrates in which acceptor substituents at the pyrazole nitrogen atom additionally play the role of protecting group. Thus, it has been shown (88M253) that iV-phenacyl- and iV-p-tosyl-4-iodopyrazoles interact with phenylacetylene, 2-methyl-3-butyn-2-ol, and trimethylsilylacetylene at room temperature for 3-24 h in 70-95% yields (Scheme 56). 

In 1988, Linstrumelle and Huynh used an all-palladium route to construct PAM 4 [21]. Reaction of 1,2-dibromobenzene with 2-methyl-3-butyn-2-ol in triethylamine at 60 °C afforded the monosubstituted product in 63 % yield along with 3% of the disubstituted material (Scheme 6). Alcohol 15 was then treated with aqueous sodium hydroxide and tetrakis(triphenylphosphine)palladium-copper(I) iodide catalysts under phase-transfer conditions, generating the terminal phenylacetylene in situ, which cyclotrimerized in 36% yield. Although there was no mention of the formation of higher cyclooligomers, it is likely that this reaction did produce these larger species, as is typically seen in Stephens-Castro coupling reactions [22]. 

Scheme 26 Formation of 1 -metallo-2-methyl-1 -cyclobutenes by the reaction of 1 -metallo-4-halo-1 -butynes with Me3AI-ZrCp2Cl2.

Somei adapted this chemistry to syntheses of (+)-norchanoclavine-I, ( )-chanoclavine-I, ( )-isochanoclavine-I, ( )-agroclavine, and related indoles [243-245, 248]. Extension of this Heck reaction to 7-iodoindoline and 2-methyl-3-buten-2-ol led to a synthesis of the alkaloid annonidine A [247]. In contrast to the uneventful Heck chemistry of allylic alcohols with 4-haloindoles, reaction of thallated indole 186 with 2-methyl-4-trimethylsilyl-3-butyn-2-ol affords an unusual l-oxa-2-sila-3-cyclopentene indole product [249]. Hegedus was also an early pioneer in exploring Heck reactions of haloindoles [250-252], Thus, reaction of 4-bromo-l-(4-toluenesulfonyl)indole (11) under Heck conditions affords 4-substituted indoles 222 [250], Murakami described the same reaction with ethyl acrylate [83], and 2-iodo-5-(and 7-) azaindoles undergo a Heck reaction with methyl acrylate [19]. 

Using NaOH as the base, diarylacetylenes have been synthesized from either 2-methyl-3-butyn-2-ol [121] or trimethylsilylacetylene [122], In both cases, NaOH unmasked the protections after the first coupling reaction, revealing the additional terminal alkynyl functionality. Therefore, coupling the adduct 141, derived from 2-iodothiophene and 2-methyl-3-butyn-2-ol, with 2-iodobenzothiophene provided diarylacetylene 142 [121], Analogously, dithienylacetylene (143) was obtained when 2-iodothiophene and trimethylsilylacetylene were subjected to the same conditions [122],... 

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). 

Steacie, E. W. R., and A. F. Trotman-Dickenson The Reactions of Methyl Radicals. IV. The Abstractions of Hydrogen Atoms from Cyclic Hydrocarbons, Butynes, Amines, Alcohols, Ethers and Ammonia. J. chem. Physics 19, 329 (1951)-... 

The monomer/oligomer mixtures were used In the third step of the reaction sequence, the replacement of bromine with 2-methyl-3-butyn-2-ol by use of the bls(trlphenylphosphlne) palladium chloride catalyst system. This reaction used a trlethylamine/pyridine solvent system to replace the bromines on the ether sulfone with ethynyl groups protected by acetone adducts. The acetone protecting groups were then removed In a toluene/methanol/potasslum hydroxide solvent system. 

Carbonylative coupling of iodobenzene with 2-methyl-3-butyn-2-ol under 65 bar carbon monoxide afforded phenylfuranones (double carbonylation) in reasonable yields (Scheme 6.32) [69]. The reaction is thought to proceed through the formation of a benzoylpalladium intermediate which either reacts with the alkynol or liberates benzoic acid hence the formation of considerable amounts of the latter. 

Methyl iodide (31) reacts with silver nitroform (32) in acetonitrile to give a 51 % yield of 1,1,1-trinitroethane (33). ° The potassium salt of nitroform in acetone has been used for the same reaction.Yields between 28 % and 65 % have been reported for the reaction of silver nitroform in acetonitrile with higher molecular weight alkyl iodides. The choice of solvent is important in some reactions, for example, silver nitroform reacts with l,4-dibromo-2-butyne (34) in solvents like dioxane and acetone to give l,l,l,6,6,6-hexanitro-3-hexyne (35) in approximately 72 % yield, whereas the same reaction in acetonitrile is reported to give a mixture of compounds. 

Several catalytic test reactions have been used for indirect characterization of acid and base properties of solids (78). Among them, decomposition of alcohols such as 2-propanol (79,80), 2-methyl-3-butyn-2-ol (81,82), 2-methyl-2-butanol (83), cyclo-hexanol (84), phenyl ethanol (55), and t-butyl alcohol (86) have been investigated. In... 

Aramendia et al. (22) investigated three separate organic test reactions such as, 1-phenyl ethanol, 2-propanol, and 2-methyl-3-butyn-2-ol (MBOH) on acid-base oxide catalysts. They reached the same conclusions about the acid-base characteristics of the samples with each of the three reactions. However, they concluded that notwithstanding the greater complexity in the reactivity of MBOH, the fact that the different products could be unequivocally related to a given type of active site makes MBOH a preferred test reactant. Unfortunately, an important drawback of the decomposition of this alcohol is that these reactions suffer from a strong deactivation caused by the formation of heavy products by aldolization of the ketone (22) and polymerization of acetylene (95). The occurrence of this reaction can certainly complicate the comparison of basic catalysts that have different intrinsic rates of the test reaction and the reaction causing catalyst decay. 

Figure 4 in Scheme 2.3-4 demonstrates that when using a triphenylphosphane-modified Ni-catalyst, butadiene reacts with 2-butyne to form a 2 1-adduct whereas with methyl 2-butynoate, a 1 2 co-oligomer is obtained. Butadiene and phenyl-acetylene also form 1 2 products As we may have shown, a change from X- to C- or Z-type substituents in the co-substrates alters the ratio from 2 1 to 1 2 in a synthon coupling reaction. 

Heitz has performed the cross-coupling polymerization using two-step one-pot process. The first step is the reaction of 1,4-diiodobenzene 107 with 2 equiv. of 2-methyl-3-butyn-2-ol 108 at room temperature in the presence of an aqueous base to give the protected bisalkyne 109. Following polycondensation with another equivalent of dihaloarene 110 leads to the corresponding polymer 111 at 100°C (Equation (53)). The overall yield of 111 was 50-90% and the average molecular weight (M ) was 1400-48 200. 

Addition of acetylene to acetone results in the formation of 2-methyl-3-butyn-2-ol, which is hydrogenated to 2-methyl-3-buten-2-ol in the presence of a palladium catalyst. This product is converted into its acetoacetate derivative with diketene [38] or with ethyl acetoacetate [39]. The acetoacetate undergoes rearrangement when heated (Carroll reaction) to give 6-methyl-5-hepten-2-one ... 

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