Hexynoic acids

Suggest reaction conditions suitable for the preparation of compound A from 5 hydroxy 2 hexynoic acid... 

Methyl 2 hexynoate has been prepared by the esterification of 2-hexynoic acid, which wras prepared by the carboxylation of sodium hexynylide.4 a,/5-Alkynoic acids have generally been obtained by either carboxylation of metal alkynylides or by eliminationreactions.5In particular, they have been prepared by the elimination of enol brosylatcs and... 

HEXYN01C ACID, methyl ester, 55, 73 2-Hexynoic acid, 5-methyl-, methyl ester,... 

Hexyllithium, 15 147 Hexyl methyl carbonate molecular formula, 6 305t l-Hexyn-3-ol, l 249t 5-Hexynoic acid, 5 34t Hexynol... 

Durley, R., Sikorski, J., Hansen, D., Promo, M. A., Webber, R. K., Pitzele, B. S., Awasthi, A. K., Moorman, A. E. (Pharmacia Corporation) 2-Amino-2-alkyl-4-hexenoic and hexynoic acid derivatives useful as nitric oxide synthase inhibitors, WO 0222559. 

Enol lactones with a halogen at the vinylic position have been synthesized as potential mechanism-based inactivators of serine hydrolyases <81JA5459). 5-Hexynoic acids (181) can be cyclized with mercury(II) ion catalysis to y-methylenebutyrolactones (182) (Scheme 41). Cyclization of the 6-bromo and 6-chloro analogues leads stereospecifically to the (Z)-haloenol lactones (trans addition) but is quite slow. Cyclization of unsubstituted or 6-methyl or 6-trimethylsilyl substituted 5-hexynoic acids is more rapid but alkene isomerization occurs during the reaction. Direct halolactonization of the 5-hexynoic acids with bromine or iodine in a two-phase system with phase transfer catalysis was successful in the preparation of various 5-halomethylene- or 5-haloethylidene-2-phenylbutyrolactones and 6-bromo-and iodo-methylenevalerolactones (Scheme 42). 

Large 2JCC couplings are observed if one or both of the coupling carbon atoms have a high character (hexynoic acid, propyne, cyclobutane ring carbons), or when the coupling path includes an electron deficient carbon atom such as a carbonyl function (Table 3.11(b)). 

Hatanaka S, Niimura Y, Takishima K, Sugiyama J (1998) (2R)-2-Amino-6-hydroxy-4-hexynoic Acid, and Related Amino Acids in the Fruiting Bodies of Amanita miculifera. Phytochemistry 49 573... 

AHA= L-2-Amino-4-hexynoic acid PP= Pyridoxal phosphate AVG= Aminoethoxy vinylglycine PG= Propyl gallate... 

Reaction of the ra-ene-5-yne carboxylic acid 977 with biscollidine iodine(l) hexafluorophosphate leads to exclusive formation of the C(6)-( )-iodovinyl tetrahydropyran-2-one 979. The product arises via attack of the acid onto the iodinium ion intermediate 978 (Scheme 258) <2004TL4503>. A similar iodolactonization of hex-5-enoic acid can be induced by Oxone -potassium iodide to furnish 6-(iodomethyl)tetrahydropyran-2-one in excellent yield (Equation 380) <2004SL368>. Similarly, treatment of 5-hexynoic acid with a polymer bound source of electrophilic iodide affords the tetrahydropyran-2-one 980 bearing a diiodo-substituted exocyclic double bond (Equation 381) <1999OL2101>. 

These spacer-free Janus bis-carbene complexes were successfully employed in the intramolecular cyclisation of acetylenic carboxylic acids (4-pentynoic acid and 5-hexynoic acid) as well as the transfer hydrogenation of ketones and imines. 

C6H802 2-hexynoic acid 764-33-0 444.11 38.541 2 7506 C6H9CI03 a-acetoxy-isobutyryl chloride 40635-66-3 328.15 27.652 1,2... 

J.A. Katzenellenbogen et al. developed an efficient method for the synthesis of alkyl-substituted enol lactones that are potent inhibitors of the serine protease elastase. The precursors for the enol lactones were a- and 3-alkyl-substituted 5-hexynoic acids, which were prepared by the bromoform reaction of the corresponding alkynoic methyl... 

Dicyclohexylcarbodiimide (DCC), N-hydroxysuccinimide (NHS), 5-hexynoic acid and di-isopropylethylamine (DIEA) were purchased from Sigma-Aldrich (Saint-Quentin-Fallavier, France). 

The sole synthesis of hybridalactone (73) is due to Corey at Harvard. The synthesis involved the use of the novel bicyclo[2.2.2]octyl ortho esters beginning with 62 (Scheme 3.5). This material, obtained from 5-hexynoic acid, was converted via the homologous trimethylsilylmethyl acetylene into allenic iodide 63 in 75% overall yield. 

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