2-propynyl alcohol

Synonyms Ethynol carbinol acetylene carbinol propiolic alcohol 2-propyn-l-ol 2-propynyl alcohol... 

Terminal allenes.1 Terminal acetylenes can be converted by a one-step reaction into terminal allenes by treatment with formaldehyde, diisopropylaminc, and copper(l) bromide in refluxing THF or dioxane. The Mannich base is an intermediate, but, surprisingly, preparation of the quaternary base is not necessary. The source of the introduced hydrogen is not clear. The highest yields are obtained with 2-propynylic alcohols, ethers, and esters. 

A mixture of dienamides was prepared from the oxime of isophorone (equation 50). Metallated 2-propynyl alcohols react with trichloroacetonitrile to form dienamides after a (3,3)-sigmatropic rearrangement and suitable prototropic shifts649 thus the dienamides formed exist as a mixture of isomers (equation 51). 

PROPYN-l-OL see PMN450 2-PROPYNYL ALCOHOL see PMN450 PROPYPHENAZONE see INYOOO PROPYTHIOURACIL see PNXOOO PROQUANIL see MQU750 PRORALONE-MOP see XDJOOO PROREX see PMI750... 

Synonyms/Trade Names 1-Propyn-3-ol 2-Propyn-1-ol 2-Propynyl alcohol ... 

Normant has reviewed the carbometallation of alkynes to give stereospecific syntheses of alkenyl-metal derivatives, and their addition to aldehydes and ketones to afford allylic alcohols. Specific titanium-catalysed 5yn-hydromag-nesiation of 2-propynylic alcohols (Scheme 16), and the related zirconium-catalysed 5yn-carboalumination of propargylic alcohol itself (also Scheme 16) or its t-butyldimethylsilyl ether (c/. 3, 139 4,160) can both lead to allylic alcohols. 

Synonyms Acetylene carbinol Ethynyl carbinol Ethynyl methanol 1-Hydroxy-2-propyne 3-Hydroxy-1-propyne Propiolic alcohol 1-Propyne-3-ol Propyn-1-ol 1-Propyn-3-ol 2-Propynol 2-Propyn-1-ol 3-Propynol 2-Propynyl alcohol Classification Unsat. aliphatic alcohol Empirical C3H4O Formula HC=CCH20H... 

The application of this methodology to suitably functionalized alkynes has allowed a direct and easy synthesis of important heterocyclic compounds starting from readily available substrates. New /1-lactone [100,101] and /3-lactam [102] derivatives were synthesized in good yields from a,a-disubstituted propynyl alcohols and amines, respectively (Eq. 38), through the mechanistic route shown in Scheme 18, path a. The substitution a to the triple bond was a necessary requisite for cychzation to occur, owing to the reactive rotamer effect [301]. 

Even more interesting was the reaction of a-substituted propynyl alcohols and amines. In this case, in fact, the initially formed 4-hydroxy-2-ynamides... 

Stereoselective Claisen-type [3,3] sigmatropic rearrangements of propynyl vinyl ethers, which are intermediates in the reaction of propynyl alcohols with aldehydes or ortho esters leading to a-allenic aldehydes or esters, have been reported15,16. 

Significantly, silylcuprates react with carbamates with syn stereoselectivity59, similar to their reactions with organocuprates62, whereas other nucleofugal groups, such as acetate or methanesulfonate, are displaced in an anti fashion23,27,57. Thus, both enantiomeric (or epimeric) allenes can be obtained from the same propynyl alcohol precursor. 

Reactions of propynyl alcohols and their derivatives with metal hydrides, such as lithium aluminum hydride, constitute an important regio- and stereoselective approach to chiral allenes of high enantiomeric purity63-69. Formally, a hydride is introduced by net 1,3-substitution, however, when leaving groups such as amines, sulfonates and tetrahydropyranyloxy are involved, it has been established that the reaction proceeds by successive trans-1,2-addition and preferred anti-1,2-elimination reactions. The conformational mobility of the intermediate results in both syn- and ami- 1,2-elimination, which leads to competition between overall syn- and anti-1,3-substitution and hence lower optical yields and/or a reversal of the stereochemistry. 

Claisen ortho ester rearrangement of propynyl alcohols of high enantiomeric purity gives the /S-allenylcarboxylic esters with diastereoselectivities of 90 10 up to 95 5110. 

Hydromagnesiation of 1-propynylic alcohols. The hydromagnesiation of alkynes (10,130) has been extended to propynylic alcohols (equation I), which provides a new route to terpenoids.1... 

Propynyl alcohols have been converted into (Z)-a-(alkoxycarbonyl)methylene /3-lactones by dialkoxycarbonylation in alcoholic media, under a carbon monoxide-air (3 1) atmosphere, using a PdVKI catalyst (Equation 37) <1997J(P1)147>. The (Z)-stereochemistry of the products was attributed to the syn nature of the carbon monoxide insertion. Substitution at the ct-alkyl position was essential to generate the lactone products in good yields. When the propynyl alcohols were cr-alkyl-unsubstituted, no /3-lactone formation was observed instead, a maleic diester and its cyclic isomer were the predominant products. Where substrates were mono-a-alkyl-substituted, yields of the /3-lactone were low, unless the alkyl group was sufficiently sterically bulky. 

A The alkynyl hydrogen of propyne is acidic and hence the propyne will form an organometallic derivative. The Grignard derivative will react with carbon dioxide to give the carboxylic acid. Cis alkenes are formed by the catalytic hydrogenation of alkynes using a Lindlar catalyst. Hence a propynyl alcohol is a precursor to compound (b). This could be obtained by the addition of a propyne anion to propanone ... 

Beilstein Handbook Reference) Acetylene carbinol Agrisynth PA AI3-24359 BRN 0506003 CCRIS 6781 EINECS 203-471-2 Ethynyl carbinol HSDB 6054 1-Hydroxy-2-propyne 3-Hydroxy-1-propyne Methanol, ethynyl- NA1986 NSC 8804 Propargyl alcohol Proplolic alcohol Propynyl alcohol 1-Propyn-3-ol ... 

Alkenes. Alk-3-en-l-ynes are obtained from dehydration of propynyl alcohols in the presence of SnCh and (Ph.iP)2PdCl2. With the same Pd complex as a catalyst carboxylic acids are degraded by one carbon. ... 

Pdl4]3 anion (generated in situ from Pdl2 in an excess of KI) at 70-80 °C and under 20 atm of a 3 1 mixture of CO and air. o] Mechanism V, path i (Scheme 19), has been proposed to explain product formation. The same catalyst proved to be effective for the conversion of 2-yn-l-ols (a,a-dialkylsubstituted, or a-monoalkylsubstituted with a sufficiently bulky alkyl group) into (Z)-3-[(alkoxycarbonyl)methylene]oxacyclobutan-2-ones with good selectivities (Scheme 22). oi Mechanism VI, path k (Scheme 19), was considered to be the most likely in this case, with the gm-dialkyl effect promoting the cyclization step (maleic diesters were mainly obtained from simple propynyl alcohol and but-3-yn-2-ol). 

Oxidative cyclocarbonylation-alkoxycarbonylation is usually observed when the reaction of alkenols and alkynols is carried out in the presence of external nucleophiles such as alcohols. /3-Lactones and /3-lactams bearing an exocyclic (Z)-(alkoxycar-bonyl)methylene moiety can be prepared according to a very simple oxidative technique starting from propynyl alcohols or amines. Geminal groups have been found to exert a powerful effect on cyclization. 

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