3-Methyl-l-butyn

In the receiver was collected almost pure 3-bromo-3-methyl-l-butyne, n 1.466B, in 50iS yield. The residue consisted of the HBr adduct of the acetylenic bromide. 

The labile hydroxyl group is easily replaced by treatment with thionyl chloride, phosphorous chlorides, or even aqueous hydrogen haUdes. At low temperatures aqueous hydrochloric (186) or hydrobromic (187) acids give good yields of 3-halo-3-methyl-l-butynes. At higher temperatures these rearrange, first to l-halo-3-methyl-1,2-butadienes, then to the corresponding 1,3-butadienes (188,189). 

Butyr aldehyde Butanal 116 C4H8O 3-Methyl-l-butyne 48 CsHs... 

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). 

Bromo-3-methyl-l-butyne from the Corresponding Carbinol and Phosphorous Tribronide... 

Its Potassium salt, deliquescent crysts Mercury salt, pltlts, dec >240°and Silver salt, voluminous ppt, explodes violently when heated have been prepd in addn to many other derivs (Ref 1) l,l-Dimethyl-2-propyn-l-nitrite 3,3-Dimethyl-l-propyn-3-ol (called Nitrite Ester of 2-Methyl-3-hutyn-2-ol in CA), HCiC.C(CH3)2.ONO mw 113.11, N 12.38% liq, hp 80-82° at 750mm press nD 1.3926 at 20° was prepd when NOCl ether were added to a stirred soln of 3 methyl-l-butyn-3-oI (parent compd)... 

Under flash vacuum thermolysis (FVT) the 1,2,3-triazine (32) was readily thermolyzed to an alkyne, a nitrile, and nitrogen in high yields. For unsymmetrically substituted 1,2,3-triazines as FVT substrates, fragmentation proceeded selectively a bulky substituent at C-4(6) made the adjacent C—N bond break more easily than the opposite C—N bond. The FVT method was applied to the synthesis of the fluorinated alkynes, perfluoro-3-methyl-l-butyne and difluoroethyne [(33), R = (CF3)2CF, F] (Equation (1)) (89CC1657, 91CC456). It has been claimed, however, that tris(dimethylamino)-1,2,3-triazine forms the monocyclic azete. 

Methyl-l-butene l,2-Dibromo-3-methylbutane 3-Methyl-l-butyne... 

However, deoxyharringtonine (110) has been synthesized (166-168) by the method summarized in Scheme 57. The lithium salt (274) of 3-methyl-l-butyne was condensed with ethyl tert-butyloxalate to give 275 which, after... 

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-pentylcyclopentanone Involved reaction of N-l-cyclopentenylpyrrol idine with 3-chl oro-3-methyl-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.9 Other indirect methods have been briefly reviewed. ... 

The FVT method can be applied for the synthesis of the fluorinated alkynes, perfluoro-3-methyl-l-butyne and difluoroethyne 40 (R = (CF3)2CF, F) (Scheme 3) <1989CC1657, 1991CC456>. It has been claimed, however, that tris (dimethylamino)-l,2,3-triazine forms the monocyclic azete. 

An Algox Pharmaceutical group reported a preparation of MNA capitalizing on a C5 + C5 strategy, and based on the alkylation of bromovaleric add (S2) with the lithium anion of 3-methyl-l-butyne (S3), followed by stereoselective reduction of 8-methyl-6-noninoic acid (S4) to ( )-MNA by dissolving-metal reduction. 

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... 

SAFETY PROFILE A poison by intravenous route. Moderately toxic by ingestion, intraperitoneal, and subcutaneous routes. Human systemic effects heart changes, cyanosis, flaccid paralysis with appropriate anesthesia. An experimental teratogen. Mutadon data reported. Potentially explosive reaction when heated with ethoxyethynyl alcohols (e.g., 1-ethoxy-3-methyl-l-butyn-3-ol). When heated to decomposition it emits toxic fumes of SOx. See also SULFATES. 

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