3-bromo-2-propyn

A coupling reaction long used in acetylene chemistry is the Cadiot-Chodkiewicz coupling [112] its use in retinoid synthesis is demonstrated by the transformations depicted in Scheme 2-19 [113], The enyne precursor 169, on Cadiot-Chodkiewicz coupling with 3-bromo-2-propyn-l-ol (170) yields the diyne 171 which, by methodology long established in retinoid chemistry [114], may either be chain-elongated to dehydroretinal 172 or — via the diynal 173 — to the bis-acetylenic retinal 174. 

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. 

QUECKSILBER (German) (7439-97-6) Violent reaction with alkali metals, aluminum, acetylenic compounds, azides, boron phosphodi iodide (vapor explodes), bromine, 3-bromo-propyne, chlorine, chlorine dioxide, ethylene oxide, lithium, metals, methyl silane (when shaken in air), nitromethane, peroxyformic acid, potassium, propargyl hromide, rubidium, sodium, sodium carbide. Forms sensitive explosive products with acetylene, ammonia (anhydrous), chlorine, picric acid. Increases the explosive sensitivity of methyl azide. Mixtures with hot sulfuric acid can be explosive. Incompatible with calcium, sodium acetylide, nitric acid. Reacts with copper, silver, and many other metals (except iron), forming amalgams. 

Reaction with l-bromopropyne-3-ols (1). Cuprous cyanide and 1-bromo-propyne-3-ols in dry DMF form rather unstable complexes of the approximate composition (CuCNja (DMF)2 RR- C(OH)C CBr. When the complex is... 

The propyne (b.p. —23.2°) is precondensed to the mark in a volumetric flask cooled by acetone-dry ice. Evaporation of some propyne during addition will lead to a moderate molar excess of l-bromo-3-chloropropane, regarded as desirable in preventing formation of diyne product. 

Propargyl Bromide (3-Bromo-l-propyne). HC=CCH2Br mw 118.97 colorl to faintly brownish liq mp 24.4° bp 88—90° d 1.52 g/cc RI 1.4320 at 20°. Sol in ale, eth, benz chlf. Flammable flash pt 10° (closed), 18° (open) ignition temp 328° lower flammable limit 3.0%. It can be decompd by mild shock. When heated under confinement, it decomps with expl violence and may detonate. When suitably diluted, as with 20—30% by wt of toluene, its expl properties are practically eliminated (Ref 4)... 

The cycloaddition of Weinreb amide functionalized nitrile oxide with a range of dipolarophiles has been studied. N-Methoxy-N-methylcarbonocyanidic amide, nitrile oxide 207 (i.e., a nitrile oxide of Weinreb amide type derivative) was generated from 2-chloro-2-(hydroxyimino)-N-methoxy-N-methylacetamide as intermediate and used in situ. Thus, addition of 3-bromo-l-propyne as dipolarophile to this precursor of 207, followed by quenching with triethylamine, gave 5-(bromo-methyl)-N-(methoxy)-N-methyl-3-isoxazolecarboxamide 208 in 55% to 60% yield (367). 

Bromo-l-propyne, see Propyne Bromoxynil, see Bromoxvnil octanoate y-BTC, see Eindane... 

Hatch. L.F. and Kidwell, L.E., Jr. Preparation and properties of 1-bromo-l-propyne, 1.3-dibromopropyne and l-bromo-3-chloro-l-prop3me, / Am. Chem. Soc., 76(l) 289-290, 1954. 

Propargyl bromide Propyne, 3-bromo- (8) 1-Propyne, 3-bromo- (9) (106-96-7) Tributyltin hydride Stannane, tributyl- (8,9) (688-73-3) Azobisisobutyronitrile Propionitrile, 2,2 -azobis[2-methyl- (8) Propanenitrile, 2,2 -azobis[2-methyl- (9) (78-67-1)... 

Dehydrobromination of 2-bromo-A, A -[bis(trifluoromethyl)]-prop-2-en-l-amine (25) gives allene 26 and propyne 27-"7 In these reactions, the bis(trifluoromethyl)amino group survives. 

Bromo-2-thienyl-thiophene-2-carbaldehyde (128), obtained from the photochemical coupling of 5-iodothiophene-2-carbaldehyde and 2-bro-mothiophene, can be reduced with NaBH4 129 was treated with propyne, copper iodide, and Pd(PPh3)4 under phase-transfer conditions to give a natural bithiophene 130 isolated from Arctium lappa (87JOC5243). 

The use of methyltriphenylphosphonium bromide and MeSOCH2 on 5-bromo-2-thienyl-thiophene-2-carbaldehyde (128) furnished the corresponding olefin 133. The reaction with propyne in this case furnished a natural bithiophene 134 isolated from Tagetes minuta (86G747). 

Bromo 2 propyne flupropadine Bromo succinimide quinmerac m. Bromotoluene see PCBA... 

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- ... 

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