Alkyne and hydroxy

Alkynyl dialkyl phosphates of the general formula RC=COPO(OR )2, were prepared by a similar spontaneous decomposition of the less stable salts RC=CI+ PhC OPO(OR)2, some of which are isolable alternatively, either alkynes and [hydroxy(dialkylphosphoryloxy)iodo]benzene or alkynysilanes and iodosylben-zene-boron trifluoride can be used [63]. 

Phase-transfer catalysis has been used successfully to annulate side-chain alkyne and hydroxy functions. 

Interestingly. 4-hydroxythiazoles (11) react like the 4-hydroxy-THISs with alkynes and alkenes (Scheme 12) (20). further demonstrating the usefulness of 4-hydroxythiazole derivatives for the preparation of 2-pyridones and thiophenes. 

Anhydro-3-hydroxy-2-phenylthiazolo[2,3-6]thiazolylium hydroxide (407) underwent ready thermal reaction with alkynic and alkenic dipolarophiles in refluxing toluene. With the former dipolarophile sulfur was lost from the intermediate 1 1 cycloadduct (408) to give the substituted 5H-thiazolo[3,2- i]pyridin-5-ones (409). With the latter, the intermediate (410) lost H2S, also forming (409). 

For this selective addition, the best catalyst precursors were Ru(methallyl)2(dppe) 1 and Ru(methallyl)2(dppb) 2. The choice of the appropriate complex depended on the steric demand of both the alkyne and the carboxylic acid. A large variety of carboxylic acids and alkynes have been used, including N-protected amino acids, a-hydroxy acids, and functionalized alkynes such as enynes, diynes and propargylic ethers [21-23] (Scheme 10.4). The addition took place under mild conditions and carboxylic adds of... 

Analysis of Chiral a-Hydroxy-Substituted Nitriles (Cyanohydrins), Alkynes and Aldehydes Noe s Lactol4,-43... 

A gold monohydride species was also suggested in the report by Ito and Sawamura et al. on the dehydrogenative silylation of alcohols by HSiEt3 and a diphosphine gold(I) complex. Reaction was selective for the silylation of hydroxy groups in the presence of alkyl halides, ketones, aldehydes, alkenes, alkynes and other functional groups [193]. 

Isomerization of a-hydroxy alkynes and alkynones 2-15 Acylation of olefins 2-27 From lithium acetylides 2-32 From vinylic organometallic compounds... 

Cyclizations with nitrogen nucleophiles involving alkynes and allenes have received little attention until recently. The cyclizations of several a-aminoallenes to 3-pyrrolines with silver tetrafluoroborate was reported by Claesson and coworkers (equation 133).264 A similar cyclization to form A -carba-penems has been reported (equation 134).265 Diastereomeric allenes (R1 R2) were shown to cyclize with complete stereocontrol. Cyclization with palladium chloride in the presence of allyl bromide or electrophilic alkenes allowed for the intermediate vinylpalladium species to be trapped by the electrophile.2651 A related product was obtained by cyclization of an alkynic substrate (equation 13S).265 Other examples of 5-endo cyclization of p-aminoalkynes50 include the formation of indoles by cyclization of 2-alkynylanilines with mercury salts200 or palladium chloride,266a,266b,266c formation of 1-pyrrolines with catalytic palladium chloride (equation 136)198 and formation of pyrroles by cyclization of hydroxy-substituted p-aminoalkynes.198,2666... 

Hydroxy(tosyloxy)iodo]benzene and Its Analogues Reactionswith Alkenes and Allenes. Reactions with Alkynes and Alcohols. Reactions with Keto Compounds. Reactions with Nitrogen, Sulfur, and Other compounds. 

The synthesis of the first alkynyliodonium tosylates was achieved by the treatment of terminal alkynes with [hydroxy(tosyloxy)iodo]benzene (HTIB) (equation 8)8,10,11. Such reactions are generally conducted with an excess of alkyne in chloroform at reflux, although they can be carried out at room temperature, and dichloromethane can be employed as solvent. This procedure is, however, restricted to terminal alkynes in which R is either an aryl group or a bulky alkyl group. With linear alkyl groups (i.e. R = n-Pr, n-Bu, fl-C5Hn), phenyl(/ -tosyloxyvinyl)iodonium tosylates are obtained instead (equation 9)8. In some cases (R = /-Pr, /-Bu), mixtures of alkynyl- and (/ -tosyloxyvinyl)iodonium tosylates are produced8. ter -Butylacetylene appears to be the optimum substrate for this approach and has been employed with a series of [hydroxy(tosyloxy)iodo]arenes for the synthesis of various aryl(ter/-butylethynyl)iodonium tosylates (equation 10)9. 

While vinylsilanes and -stannanes have been used primarily for the synthesis of vinyliodonium salts with one or two / -alkyl substituents in the vinyl moiety, the treatment of alkynes with oxyiodanes permits the introduction of oxygen functionality at jft-carbon. The conversion of terminal alkynes with [hydroxy(tosyloxy) iodo]benzene (HTIB) to alkynyliodonium tosylates (equation 8) and/or (j5-tosyloxyvinyl)iodonium tosylates [TsOC (R)=CHiPh, "OTs R = n-Pr, n-Bu, n-C5Hn, i-Pr, i-Bu] (equation 9), depending on the size of R, has already been discussed8,11. In at least three cases, E Z mixtures were... 

Iminocoumarins are formed in high yield from the Cu-catalysed multicomponent reaction of salicylaldehyde, alkynes and sulfonyl azides. It is considered that an initially formed ketimine reacts with the salicylaldehyde hydroxy function and an intramolecular nucleophilic addition to the aldehyde moiety completes the sequence (Scheme 29) <06OL4517>. 

BuLi and AC2O of nitrooxaheptynes 20, generated in high yields from nitroalkenes and hydroxy alkynes <03H(59)685>. 

Alcohols can undergo photoaddition to alkynes, and the products from acetylenic esters are Y-hydroxy-rra//j-a,j3-unsaturated esters or the unsaturated lactones derived from the cis isomers by cyclization (equation 21). Reaction with acetylenic ketones provides a route to furans (equation 22) , and there is n.m.r. evidence for... 

FVP experiments were carried out between 500 and 800 °G on 3(5)-phenyl- and 3(5)-methylpyrazolinones and on 3(5)-methoxy-5(3)-phenylpyrazole < 1999J(P2)211 >. The origin of the isolated products (mainly indanone, hydroxy-alkynes, and a,/ -unsaturated aldehydes) were explained as arising from the hydroxy tautomers of pyrazolinones. Temperature effects on the tautomeric equilibrium of 1-phenyl-3-methylpyrazolinone in solution show that the percentage of the GFI tautomer increased with increasing temperature. 

Carbenes have also been considered as intermediates in the thermal dissociation of 2-alkoxy-l,3-dithioles (Section III,B,4) and in the reactions of carbon disulfide with activated alkynes and with benzyne. Another type of deprotonation may occur with 1,3-dithiolium cations containing phenolic hydroxyls. Thus, treatment of 4-aryl-2-(4-hydroxy-phenyl)-1,3-dithiolium perchlorate with triethylamine gives 135, stabilized by its zwitterionic structure 136. ... 

Tandem chain extension at both the 1-alkyne and propargylic positions of 1-alkynes by sequential (1) alkylation and (2) hydroxy-alkylation (1,2-addition) of 1,3-dilithiated alkynes provides an attractive, one-pot preparation of functionally disubstituted alkynes. The required 1,3-dilithiated species are obtained by lithiation of 1-alkynes at both the 1- and 3- positions with two equivalents of n-BuLi in the presence of TMEDA (tetramethylethylenediamine). The two-stage chain extension depicted below for propyne involves initial alkylation of the dilithiated propyne with the less reactive electrophile, n-BuBr, at the more nucleophilic propargylic position. Subsequent hydroxyalkylation at the less nucleophilic alkynylide position with the more electrophilic formaldehyde furnishes the a-hydroxyalkyne. ... 

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