1- phenyl-2-butyne

The reactivity of dichloro carbene towards acetylenic bonds was systematically investigated by Dehmlow19, 20 with respect to substitution of the acetylene, especially those containing additional C-C multiple bonds. It was shown that with aiyl alkyl acetylenes, e.g. 1-phenyl-butyne-l, often the normal cyclopropenone formation occurs only to a minor extent (to yield, e.g. 14), whilst the main reaction consists of an insertion of a second carbene moiety into the original acetylene-alkyl bond (giving, e.g. 15) ... 

Write structural formulas for the following compounds (a) traw5 -2-pentene, (b) 2-ethyl-l-butene, (c) 4-ethyl-fra i -2-heptene, (d) 3-phenyl-butyne. 

Scheme 31.1 (a) The products obtained from the catalytic reaction of 4-phenyl-butyne (19) with 18 both in the presence and absence of water [53a]. (b) Addition of TMSN3 to isonitriles to obtain a series of substituted IH-tetrazoles [53d]. (c) 1,3-Cycloaddition reaction between diazoacetate esters (26) and electron-poor alkene (27) to obtain 4,5-dihydro-IH-pyrazole derivatives (28) [53e]... 

Pyrazoles are formed when the diazo compounds react with alkynes or with functionalized alkenes, viz. the enols of /3-diketones. Pyrazolenines (353 Section 4.04.2.2.1) are isolated from disubstituted diazomethanes. Many pyrazoles, difficult to obtain by other methods, have been prepared by this procedure, for example 3-cyanopyrazole (616) is obtained from cyanoacetylene and diazomethane (7iJCS(C)2i47), 3,4,5-tris(trifiuoromethyl)pyrazole (617) from trifluorodiazoethane and hexafluoro-2-butyne (8lAHC(28)l), and 4-phenyl-3-triflylpyrazole (618 R =H) from phenyltriflylacetylene and diazomethane (82MI40402). An excess of diazomethane causes iV-methylation of the pyrazole (618 R = H) and the two isomers (618 R = Me) and (619) are formed in a ratio of 1 1. 

Perfluoro-2-butyne is, as expected, even more reactive in its reaction with phenyl azide [75]. Its reaction with 7V-phenylsydnone is also reported [79] (equation 13). 

Imagine that another reaction similar to that in Problem 9.81 is carried out between sodium acetylide and (R)-2-phenylpropana) to yield 1-phenyl-3-butyn-2-ol ... 

Formation of rearranged products in the solvolysis of homopropargyl systems need not involve triple-bond participation and vinyl cations in all instances. Ward and Sherman investigated the formolysis of 4-phenyl-1-butyn-l-yl brosylate, 57 (80). At 80°C in the presence of one equivalent of pyridine, they observed formation of phenyl cyclopropyl ketone, 58, and... 

Dimethyl-1-butyne (0.92 mL, 0.62 g, 7.52 mmol) is added to a solution of l methoxy(phenyl)carbene]pentacarbonylchromium (1.56 g, 5.00 nimbi) in tert-butyl methyl etoer (25 mL), and the resulting mixture is stirred at 45 °C under argon for 2 h. Concentration under reduced pressure and column chromatography... 

Ketones containing triple bonds in the a,)3-positions are reduced to the corresponding unsaturated alcohols with sodium cyanoborohydride or tetra-butylammonium cyanoborohydride in 64-89% yields [780]. Thus 4-phenyl-3-butyn-2-one gave 4-phenyl-3-butyn-2-ol [780]. If the same ketone was converted to its p-toluenesulfonylhydrazone and this was reduced with bis benzyloxy)borane, 1-phenyl-1,2-butadiene was obtained in 21% yield [786]. 

Procedure for KR of a propargylic iec-alcohol using catalyst 16 KR of ( )-4-phenyl-3-butyn-2-ol [83]... 

A vial containing ( )-4-phenyl-3-butyn-2-ol (73.0 mg, 0.500 mmol) and catalyst 16 (3.3 mg, 0.005 mmol) in tert-amyl alcohol (1.0 mL) was capped with a septum and sonicated to help dissolve the catalyst. The resulting purple solution was cooled to 0 °C, and Ac O (35.4 pL, 0.375 mmol) was added by syringe. After 49 h, the reaction mixture was quenched by the addition of a large excess of MeOH. After concentration in vacuo, the residue was purified by FC on sihca gel (EtOAc/hexanes, 1/9 — 1/1 then EtOAc/hexanes/ EtjN, 9/9/2) to afford the (l )-acetate (68.6% ee by chiral-GC) and the (5)-alcohol (96.0%ee by chiral-GC on the acetate obtained following esterification). The calculated selectivity value at 58.3% conversion was s = 20.2. 

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. 

If photochemical apparatus is not available, the cycloisomerization reaction can be conducted using trimethylamine N-oxide to promote oxidative decarbonylation of molybdenum hexacarbonyl in a mixture of EtjN and EtgO, followed by addition of 1-phenyl-3-butyn-1-ol (1). In the submitters hands, this procedure required somewhat higher loading of molybdenum hexacarbonyl, and purification of the 2-phenyl-2,3-dihydrofuran (2) product required silica gel chromatography. 

Phenyl-2,3-dihydrofuran Furan, 2,3-dihydro-2-phenyl- (8,9) (33732-62-6) 1-Phenyl-3-butyn-1-ol Benzenemethanol, a-2-propynyl- (9) (1743-36-8)... 

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. 

---