1 -Alkynyl p-

Allenyl and 1- and 2-alkynyl sulfoxides have also been prepared by reaction of organomagnesium halides with sulfinate ester 19. 1-Alkynyl p-tolyl sulfoxides were prepared in good yield from 1-alkynylmagnesium halides plus ester 19 in toluene (equation ll)63. The corresponding organolithium compound was unsatisfactory as a... 

The preparation of optically pure ( )- and (Z)-l-alkenyl p-tolyl sulfoxides was described via stereoselective reduction of 1-alkynyl p-tolyl sulfoxides (eq 6). ... 

McDowell and Stirling194 studied electronic effects upon the reactivity of aryl vinyl sulfones towards amines. Rate constants for t-butylamine addition in ethanol at 25 °C were well correlated by the Hammett equation, with p = 1.59. Comparison of this with p values for H-D exchange mentioned above191 suggested considerable carbanionic character in the transition state, perhaps in a concerted mechanism. Rates of addition of amines to alkenyl, allenyl and alkynyl p-tolyl sulfones have also been measured195. 

C. Reactions not involving P=0 or P=S Groups.—Enamine phosphine oxides (45) have been prepared by the addition of amines to 1-alkynyl-phosphine oxides, and the reactions of their anions with various electrophiles have been reported. - With ketones a Wittig-type reaction leads to the formation of a/3-unsaturated ketones, in 53—70% yield, while with epoxides cyclopropyl ketimines are formed. A Diels-Alder reaction of l-phenyl-A -phospholen-l-oxide (46) with 1,4-diacetoxybutadiene has been used in the preparation of l-phenyl-benzo[/>]phosphole (47), as... 

Alkenyl p-tolyl sulfoxides.1 Various 1-alkynylmagnesium bromides react stereospecifically (with inversion) with 1 in ether/toluene to give chiral 1-alkynyl sulfoxides 2. Reduction of 2 with LiAlH4 (THF, - 90°) affords optically pure (E)-1-alkenyl p-tolyl sulfoxides (3). The corresponding (Z)-isomers are obtained by hydrogenation of 2 with the Wilkinson catalyst. 

Alcaide et al. (68,69) recently published their smdies of the intramolecular 1,3-dipolar cycloaddition reactions of alkynyl-p-lactams in which they found that the desired cycloaddition was in competition with a reverse-Cope elimination. The reaction of alkynyl aldehydes 37a-c with Al-methylhydroxylamine afforded a mixture of products depending on the reaction conditions and the chain length separating the alkyne and the lactam (Scheme 1.8). Thus, up to three separate... 

The metal centres in the iron, ruthenium, and osmium alkynyl complexes listed in Table 1 possess 18 valence electrons. Table 2 contains HRS data at 1.064 p,m and two-level-corrected values for similar 18 valence electron alkynyl and chloro nickel complexes, and a particularly efficient example is illustrated in Figure 5. These data are substantially resonance enhanced, although the relative orderings are maintained with two-level-corrected values. 

Morrall et al. review NLO properties of iron, ruthenium, osmium, nickel, and gold alkynyl complexes, which the authors have prepared. HRS (at 1.064 p,m) and Z-scan (at 0.8 p,m) measurements have been employed. Structure-property relations have been established. Static first hyperpolarizability values have also been computed employing the two-state model. They relate the NLO coefficients to several factors and properties (e.g. ease of oxidation, ir-system length, dimensionality ). 

Oxidative addition [1, 38] of 1-alkenyl, 1-alkynyl, allyl, benzyl, and aryl halides to a palladium(O) complex affords a stable trans-o-p al 1 adi u m( 11) complex (11). The reaction proceeds with complete retention of configuration for alkenyl halides and with inversion for allylic and benzylic halides. Alkyl halides having /5-hydrogens are rarely useful because the oxidative addition step is very slow and may compete with /5-hydride elimination from the <7-organopalladium(II) species. However, it has been recendy shown that iodoalkanes undergo the cross-coupling reaction with organoboron compounds (Section 2.4.5). 

Alkynyl ethers bearing hydrogen atoms p to the oxygen atom fragment readily into an alkene and a ketene at moderate temperatures. Semi-empirical calculations are consistent with the reaction having a highly synchronous character, and fit the observed isotope effects... 

Reaction of alkynyl(p-phenylene)bis-iodonium ditriflates 34 with sodium phenoxide in methanol provides 2-substituted benzofurans in 49-62% yields. The starting materials 34 were prepared readily by interaction of 33 with 1-trimethylsilylalkynes <97JCS(P2)1511>. 

In 2008, Li et al. reported a copper-catalyzed amine-alkyne-alkyne addition reaction as an efficient method for the synthesis of Y,5-alkynyl-p-amino acid derivatives 102 (Scheme 3.52) [137]. In this case, the first step of the reaction is proposed to be the hydroamination of the electron-deficient alkyne 100, which plays the role of the aldehyde component. Subsequent reaction of the resultant intermediate XXX with alkyne 101 would afford intermediate XXXI, which would be then protonated to give an iminium intermediate XXXII. Finally, an intramolecular transfer of the alkyne moiety to the iminium ion would yield the 7,8-alkynyl-p-amino ester 102 and regenerate the catalyst. The reaction was later extended using chiral prolinol derivatives as the amine component, which afforded the corresponding Y,5-alkynyl-p-amino acid derivatives with excellent diaste-reoselectivities (up to >99 1) [138]. 

Diastereoselective synthesis of cyc/o-saligenyl nucleoside phosphotriesters has been achieved using two diastereopure 3-methyl-cyc/o-Sal-phospho-triesters, e.g. (1, nucleoside phosphotriester derivatives of AZT and d4T were prepared and it was found that the antiviral activity was between five and 20-fold different between the individual diastereoisomers. A series of C5-substituted alkenyl- alkynyl- and aryl-dUMP derivatives was synthesised and assayed against the flavin-dependent thymidylate synthase ThyX from Mycobacterium tuberculosis. Of these some were found to be active at submicromolar concentration with specificity for ThyX compared with a bacterial thymidylate synthase. Eleven triazole nucleoside monophosphates (2) were synthesised, with inhibitory effects against bacterial NAD-dependent malic enzyme. ... 

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