Methyl-2-propynyl ether

C8H14 1,2-dimethylcyclohexene 1674-10-8 411.13 34.721 1,2 14582 C8H140 tert-butyl 1-methyl-2-propynyl ether 26826-40-4 443.32 38.466 2... 

Methyl-2-propynyl ether (methyl propargyl ether) [627-41-8]... 

Fig. 5.20 Structures of rert-butyl acetylene and rert-butyl l-methyl-2-propynyl ether. These two strueturally similar acetylenic compounds contain the rert-butyl moiety...

ROC==CCH -> ROCHjC CH. Propynyl ethers can be obtained from secondary alkoxides by reaction with trichloroethylene followed by dehydrochlorination and methylation. These can be rearranged to propargyl ethers by KAPA. This sequence is applicable to highly hindered secondary alcohols.1... 

Pyran dervatives have been synthesised from the cyclisation of propynyl ethers. Thus 8-methyl-7-hydroxycoumarin was converted in 72% yield with... 

The alkynylation of estrone methyl ether with the lithium, sodium and potassium derivatives of propargyl alcohol, 3-butyn-l-ol, and propargyl aldehyde diethyl acetal in pyridine and dioxane has been studied by Miller. Every combination of alkali metal and alkyne tried, but one, gives the 17a-alkylated products (65a), (65c) and (65d). The exception is alkynylation with the potassium derivative of propargyl aldehyde diethyl acetal in pyridine at room temperature, which produces a mixture of epimeric 17-(3, 3 -diethoxy-T-propynyl) derivatives. The rate of alkynylation of estrone methyl ether depends on the structure of the alkyne and proceeds in the order propar-gylaldehyde diethyl acetal > 3-butyn-l-ol > propargyl alcohol. The reactivity of the alkali metal salts is in the order potassium > sodium > lithium. 

Mono- and di-alkylated furans were synthesized in a one-pot preparation from 2-propynyl-2-tetrahydropyranyl ether (106), butyllithium and formaldehyde. The intermediate allenyl ether (107) presumably cyclizes via a 2-(2-tetrapyranyloxy)-2,5-dihydrofuran (108) to afford the heterocycle (109) (79AG(E)875). In a similar manner, singly and doubly branched tetrahydropyranyloxybutynolates afforded the substituted furans (110) (Scheme 20). The thermocatalytic isomerization of ethyl l-methyl-2-phenylcyclopropene-3-carboxylate yielded the furan, possibly by a 1,3-sigmatropic displacement step or by a non-concerted biradical intermediate (75T2495). 

In the same way, substituted vinyl alcohols 93 are readily converted into 2-methyl-l,3,6-trioxocan propynyl-<2003RJ01384> or polyfluoroalkyl- <2002KGS1419> ethers (Equation 12), difficultly accessible by other methods. The cyclization is promoted by trifluoroacetic acid in boiling dry diethyl ether and affords high yields of the products. 

GL-Trimethylsilyl-oi, -enones.ls These useful Michael acceptors (2) can be prepared by rearrangement of l-(trimethylsilyl)-2-propynyl trimethylsilyl ethers (1) with methyl-aluminum dichloride. 

Di-(2-propynyl)-3-methyl-5-methylene-2-isoxazoline heated 15 min. at 140-145° under Ng with temporary cooling to control the exothermic reaction 5-(2,3-butadienyl)-3-methyl-4-(2-propynyl)isoxazole (Y 77.0%) dissolved in ether, and passed at room temp, through AlgOj 5-(l,3-butadienyl)-3-methyl-4-(l,2-propa-dienyl)isoxazole (Y 93.8%). D. T. Manning and H. A. Coleman, J. Org. Chem. 34, 3248 (1969). 

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