Diacetylene alcohols

Furan derivatives are formed when aqueous solutions of amines react with diacetylenic alcohols and glycols. Thus when 155 is heated with aqueous dimethyl-amine, the aminofuran 158 is formed . The initial steps involve amine addition and hydration giving 156 which suffers dealdolization to give the ketone 157. In the case of tertiary glycols such as 159, a similar sequence of steps followed by hydrolysis of the intermediate enamine produces the furanone 160 . ... 

Dioxolanes 162 are formed by the reaction of diacetylenic alcohols with aldehydes and ketones in the presence of base -. The initial step involves formation of the... 

Some 2//-pyrans were obtained by cyclization of alkenic acetylenes after their activation involving C=C — C=C exchange in initial reaction steps. Thus, diacetylenic alcohol PhCH(OH)C=C—C=CPh (56) was found to cyclize to 2//-pyrans readily after the addition of secondary amines RR NH (82CZ296). Similarly, acetylenic ketone PhCOC=C—CH=CHOMe (57) gave appropriate 2//-pyrans after the addition of aqueous bromine or benzthiamide (83AP454). 

This reaction is common to butadiynes containing alkyl, aryl, or heterocyclic groups and to primary, secondary, and tertiary diacetylenic alcohols. 

Packter, N.M. Studies on the Biosynthesis of Phenols in Fungi. Production of 4-Methoxytoluquinol, Epoxysuccinic Acid and a Diacetylenic Alcohol by Surface Cultures of Lentinus degener I.M.I. 110525. Biochem. J. 114, 369 (1969). 

The lithium orthopropyolate 194 was prepared by a silicon-lithium exchange from the trimethylsUylacetylene derivative 193 and reacted with acetylenic aldehydes to give diacetylenic alcohols 195, which were easily transformed into the corresponding ketones by treatment with manganese dioxide (Scheme 2.26) [162]. 

As in the reaction of diacetylene with alcohols (00UK642), the addition of glycols seems to start with attack at the terminal carbon atom of diacetylene, but no intermediate hydroxyl-containing enyne ether was isolated. 

The synthesis of thiophene from diacetylene was first performed by Schulte (62CB1943), who used sodium sulfide in aqueous alcohol (pH 8-10), the yield being no more than 20%. 

As mentioned in the introduction, l-heterobut-l-en-3-ynes, RXCH=CHC=CH (X = RN, O, S R = organic radical), are the nearest and most important diacetylene derivatives readily formed by nucleophilic addition of amines, alcohols, and thiols to diacetylene. In many heterocyclization reactions (especially those leading to fundamental heterocycles) l-heterobut-l-en-3-ynes behave as diacetylene synthetic equivalents, but unlike diacetylene, they are nonhazardous. Therefore, the syntheses of heterocycles therefrom are often more attractive in preparative aspect. 

Coupling of excess (Z)-l,2-dichloroethene (217) with propargyl alcohol first led to the enyne 218, which, when subjected to a second Pd-catalyzed coupling step with trimethylsilylacetylene, provided the mixed diacetylene 219. With all carbon atoms assembled, the allene function was generated by first producing the (unprotected) hydrazine derivative 220, which on treatment with either diethyl azodicarboxylate (DEAD) or 4-methyl-l,2,4-triazoline-3,5-dione (MTAD) under anaerobic conditions at 0 °C yielded the hydrocarbon 27. According to mechanistic studies, the latter process leads first to a mixture of ( )- and (Z)-diazenes. Sigmatropic elimination of... 

The free y hydroxy-acetylenic acids in the thiophene series are very unstable and trimerize very readily. The ease of dimerization and trimerization of acetylenic compounds in the presence of a hydroxyl group, conjugated double bond or a second triple bond is very characteristic and was observed with certain acetylenic alcohols and diacetylenic glycols in this series. 

Enyne ethers HC=CCH=CHOR are useful synthetic intermediates. They can be prepared by base-catalysed addition of alcohols to diacetylene. The required conditions are rather forcing and not very attractive for laboratory scale preparations. A much more convenient way to prepare the enyne ethers (in these cases more than 80 rel.% of the -isomer is obtained) consists in treatment of the easily accessible 1,4-dialkoxy-2-alkynes with two equivalents of alkali amide in liquid ammonia. The first step in this elimination is the (transient) formation of an "anion RO-fiH-C CCH OR, which eliminates ROH (143). The resulting cumulenic ether ROCH=C=C=CH2 is immediately converted into the metallaied enyne ether. 

Rearrangement of Disubstituted Amino Diacetylenic Tertiary Alcohols to Ynamines [12]... 

Air, the cheapest oxidant, is used only rarely without irradiation and without catalysts. Examples of oxidations by air alone are the conversion of aldehydes into carboxylic acids (autoxidation) and the oxidation of acyl-oins to a-diketones. Usually, exposure to light, irradiation with ultraviolet light, or catalysts are needed. Under such circumstances, dehydrogenative coupling in benzylic positions takes place at very mild conditions [7]. In the presence of catalysts, terminal acetylenes are coupled to give diacetylenes [2], and anthracene is oxidized to anthraquinone [3]. Alcohols are converted into aldehydes or ketones with limited amounts of air [4, 5, 6, 7], Air oxidizes esters to keto esters [3], thiols to disulfides [9], and sulfoxides to sulfones [10. In the presence of mercuric bromide and under irradiation, methylene groups in allylic and benzylic positions are oxidized to carbonyls [11]. 

Oxidation of the alcoholic group in acetylenic alcohols is discussed in previous sections (equations 218, 219, 250, 254, and 272). Oxidations affecting the rest of the molecule, that is, acetylenic hydrogen, are shown in equation 283. Such oxidations are carried out analogously to those of simple terminal acetylenes and lead to diacetylenic diols [2, 5S]. 

Diacetylene or Butadiyne (called Diacetylen or Butadiin in Get), HCiC.C. CH raw 50,06 gas at RT having a pronounced odor, forms Ifts on cooling with liq air, fr p -36 bp 10° at 760mm press, d 0,7364 at 0°, nj 1,4386 at 0,87 can be prepd by the action of cupric chloride soln on cuprous acetylide, followed by treatment of the Cu diacety-lide,thus formed,with dil HCl and by action of excess alcoholic KOH at 150-60° on butadiene tecrabromide and by other methods (Refs 1 2 ... 

We protect one hydroxyl terminus of the commercially available 1,8-octane diol 1 by reaction with dihydropyran to give the monoalcohol, 8-tetrahydropyranyloxyoctanol 2. The protected alcohol 2 is oxidized to the aldehyde with pyridinium chlorochromate to give 8-tetrahydropyranyl-oxyoctanal 3. 1-Heptyne 4 is coupled with propargyl bromide 5 in a copper catalyzed reaction to produce the diacetylenic 1,4-decadiyne 6. 

Addition of alcohols to diacetylene is substantially easier methanol affords 3-butyn-l-enyl methyl ether.193 Tri- and tetra-acetylenic compounds react still more rapidly.196... 

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