3.3- dimethyl-3- -propyne

Another strategy for MTI 800 is based on the 3(4-ethoxyphenyl)-3,3-dimethyl-propyne 416 for a classical reaction with an aldehyde (Scheme 274). 

Methylisoxazole (297 R = Me) and its homologs can be synthesized by reaction of hydroxylamine hydrochloride with 1-alkyl-3-dimethylamino-2-propen-l-one (296) (54IZV47), the anilino derivatives of acetoacetaldehyde (47G556), 3-dimethyl-aminomethylene-l-propyne (equation 7) (69ZOR1179) and the /3-ketoaldehyde (293) (66JOC3193). 

Bis(trimethylsilyl)propyne, 141 Bis(trimethylsilyl)terminai alkynols, 97 Borane-dimethyl sulphide. 84 Bromination-dcsilicobromination, 17-18... 

The regiochemistry of Al-H addition to unsymmetrically substituted alkynes can be significantly altered by the presence of a catalyst. This was first shown by Eisch and Foxton in the nickel-catalyzed hydroalumination of several disubstituted acetylenes [26, 32]. For example, the product of the uncatalyzed reaction of 1-phenyl-propyne (75) with BujAlH was exclusively ds-[3-methylstyrene (76). Quenching the intermediate organoaluminum compounds with DjO revealed a regioselectivity of 82 18. In the nickel-catalyzed reaction, cis-P-methylstyrene was also the major product (66%), but it was accompanied by 22% of n-propylbenzene (78) and 6% of (E,E)-2,3-dimethyl-l,4-diphenyl-l,3-butadiene (77). The selectivity of Al-H addition was again studied by deuterolytic workup a ratio of 76a 76b = 56 44 was found in this case. Hydroalumination of other unsymmetrical alkynes also showed a decrease in the regioselectivity in the presence of a nickel catalyst (Scheme 2-22). 

In the course of investigation of reactivity of the mesoionic compound 44 (Scheme 2) the question arose if this bicyclic system participates in Diels-Alder reactions as an electron-rich or an electron-poor component <1999T13703>. The energy level of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) orbitals were calculated by PM3 method. Comparison of these values with those of two different dienophiles (dimethyl acetylenedicarboxylate (DMAD) and 1,1-diethylamino-l-propyne) suggested that a faster cycloaddition can be expected with the electron-rich ynamine, that is, the Diels-Alder reaction of inverse electron demand is preferred. The experimental results seemed to support this assumption. 

Instead of alanine and valine, several other chiral auxiliaries have been used, such as tert-leucine13, leucine14 and isoleucine15. In some cases diastereomeric excesses may be higher with the dihydropyrazines 5 and 6, derived from 0,0-dimethyl-alkylation with 3-bromo-propyne gives a de of 60% with (2S)-2,5-dihydro-2-isopropyl-3,6-dimethoxypyrazine (3), in contrast to 85% de with 516 and >95% de with 613. 

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)... 

Dipolar cycloaddition of anhydro pyrido[2,l-b][l,3]thiazinium hydroxides (128) with aryl isocyanates and dimethyl acetylenedicarboxylate gave pyrido[l,2]pyrimidines (129) and quinolizine-l,2-dicarboxylates (130), respectively (76CB3668). 1,4-Dipolar cycloaddition of pyrido[2,l-h][l,3]thi-azinium betaine (131, R = Me) with 1-diethylamino-l-propyne afforded cycloadduct 132, from which quinolizin-4-one 133 formed by a rapid cheletropic extrusion of carbonyl sulfide (93TL5405 95T6651). 1,4-Dipolar cycloaddition of anhydro 4-hydroxyl-2-oxo-6,7,8,9-tetrahydro-2//-pyrido-[2,l-b][l,3]thiazinium hydroxides (131) and 4-phenyl-l,2,4-triazoline-3,5-dione yielded 135 via 134 [94H(39)219 95H(41)1631] and 136 (95T6651). 

HC=CCH3 hc=cch2ch3 CH3C=CCH3 (CH3)3CC=CCH3 Propyne 1-Butyne 2-Butyne 4,4-Dimethyl-2-pentyne... 

List B, giving examples of liquids where a degree of concentration is necessary before hazardous levels of peroxides will develop, includes several common solvents containing one ether function (diethyl ether, ethyl vinyl ether, tetrahydrofuran), or two ether functions (p-dioxane, 1,1 -diethoxyethane, the dimethyl ethers of ethylene glycol or diethylene glycol ), the secondary alcohols 2-propanol and 2-butanol, as well as the susceptible hydrocarbons propyne, butadiyne, dicyclopentadiene, cyclohexene and tetra- and deca-hydronaphthalenes. Checking stocks at 12 monthly intervals, with peroxidic samples being discarded or repurified, is recommended here [1],... 

The reaction of acetylenes with CO to produce octatrienediolides has been reported (2a). In the presence of dicobalt octacarbonyl in acetic anhydride/ acetone solvent, propyne was found to react with CO to give dimethyl-octatrienediolides. Hydrogenation of the latter yielded 2,6-dimethylsuberic acid. 

The (R) allene 121 was obtained with high anti stereoselectivity in the reaction of (i )-(—)-l-trifluoroacetoxy-l-phenyl-2-propyne (120) with PhZnCl. 2-Alkynyloxiranes react smoothly with alkynyl, alkenyl and arylzinc reagents. Reaction of 2-methyl-2-(l-propynyl)oxirane (122) with vinylzinc chloride (123) yields 2,4-dimethyl-2,3,5-hexatrien-l-ol (124) [31],... 

The use of Rh2(5/ -MEPY)4 and Rh2(55-MEPY)4 for reactions with menthyl diazoacetates (MDA) also produces an enormous double diastereoselection not previously observed to the same degree in cyclopropanation reactions. With methyl propargyl ether, for example, Rh2(5/ -MEPY)4 catalyzed reactions of d-MDA yield 16 (R = CH3OCH2) in 98% diastereomeric excess (de), but /-MDA produces its diastereoisomer in only 40% de with Rh2(55-MEPY)4, /-MDA gives the higher de (98%) and d-MDA gives the lower de (43%). Similar results are obtained from reactions of MDA with 1-hexyne and 3,3-dimethyl-1-propyne. The diazocarboxylate substituent obviously plays a critical role in establishing the more effective carbene orientation for addition to the alkyne. 

Propanedithiol (109-80-8), 65, 150 2-Propanol, titanium (4+) salt, 65, 230 2-Propanone, l-bromo-3-chloro-, dimethyl acetal, 65, 32 PROPARGYL CHLORIDE PROPYNE, 3-CHLDRD- 1-PROPYNE, 3-CHL0RD- ... 

Propargyl bromide 1-Propyne, 3-bromo- (8,9) (106-96-7) Dimethyl acetylenedicarboxylate Acetylenedicarboxylic acid, dimethyl ester (8) 2-Butynedioic acid, dimethyl ester (9) (762-42-5) l,2-Hexadien-5-yne (8,9) (33142-15-3)... 

III. If water is added to propyne, dimethyl ketone (2-propanone) is produced. 

Irradiation of [68] at room temperature results in low yields of acetylene, propyne, and butyne. Dimethyl-tetrahedrane is a speculative intermediate in this photolysis (63). 

Many solvents form dangerous levels of peroxides during storage e.g., dipropyl ether, divinylacetylene, vinylidene chloride, potassium amide, sodium amide. Other compounds form peroxides in storage but concentration is required to reach dangerous levels e.g., diethyl ether, ethyl vinyl ether, tetrahydrofuran, p-dioxane, l,l-diethox) eth-ane, ethylene glycol dimethyl ether, propyne, butadiene, dicyclopentadiene, cyclohexene, tetrahydronaphthalenes, deca-hydrona-phthalenes. Some monomeric materials can form peroxides that catalyze hazardous polymerization reactions e.g., acr) lic acid, acr)Ionitrile, butadiene, 2-chlorobutadiene, chlorotrifluoroethylene, methyl methacrylate, styrene, tetrafluoroethylene,... 

Property Poly[ 1 -(trimethyl-silyl)-l-propyne Poly(dimethyl- siloxane)... 

C8H10O4 3,4-dihydro-2,2-dimethyl-4-oxo-2H-pyran-6-ca 80866-93-9 23.00 1.1085 2 14249 C8H12 3-cyclopentyl-1 -propyne 116279-08-4 25.00 0.8200 1... 

Dimethyl-4-oxo-4-phenyl-/ -4//-l,4-telluraphospliorin This reaction must be performed under a nitrogen atmosphere. 17.4 g (100 mmol) of disodium telluride are prepared from 4.6 g (200 mmol) of sodium and 12.8 g (100 mmol) of tellurium in liquid ammonia. When the reaction between sodium and tellurium is complete, 175 ml of methanol are cautiously added to the sodium telluride suspension in liquid ammonia. The ammonia is allowed to evaporate, and the mixture is then heated on a water bath kept at 40°. Methanol is added to bring the volume to 150 ml. 6.1 g (30 mmol) of bis[l-propyn-1-yl](phenyl)phosphine oxide are added, the mixture is stirred for 5 h, 500 m/ of ice/water are added, and the resultant mixture is extracted several times with chloroform. The combined extracts are filtered, and the filtrate is washed with water, dried with anhydrous magnesium chloride, and filtered. The solvent is evaporated from the filtrate under aspirator vacuum and the residue is recrystallized several times from toluene yield 7.0g (71%) m.p. 179-182°. Similarly prepared were the following compounds ... 

Dimetbyl 2 pTOpyn-l-ol or l-propyn-3-ol (called 2-MethyI-3-buryn-2-ol in CA and Dimethyl-acetylenylcarbinol or Dimethyl-athinyl carbinol in Ger,... 

Isomerization Isomerization of safrole to isosafrole, of 2,3-dimethyl-1-butene and of 3,5-vinylbicyclo[2.2.1]heptene Isomerization of 1,2-propadiene to propyne Na/NaOH/AljO, K2O/AI2O3... 

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