Propargylic alcohols, use

The procedure described is that of Wille and Saffer. Propiolaldehyde has also been prepared by the oxidation of propargyl alcohol using ammonium dichromate or manganese dioxide in 10% sulfuric acid. Propiolaldehyde has also been prepared by warming the dimethyl or diethyl acetal with dilute sulfuric acid. ... 

A series of ethynyl ketones and ethynylketoesters were reduced enantioselectively to the corresponding nonracemic propargyl alcohols using a secondary alcohol dehydrogenase from... 

Shortly after this work, Shibasaki and coworkers developed a useful method for the substitution of allyl and propargyl alcohols using Bi(OTf)3 [61]. Various amines such as tosylamine, carbamates, amides and cinnamylamide yielded allyl and propargyl amides 27a-h and 25g-h in excellent yields (Scheme 21). The addition of KPF6 was... 

Scheme I Working hypothesis to activate allylic and propargylic alcohols using a Bi catalyst via cj-71 chelation...

Scheme 2.2.4.4 Reduction of alkynones to chiral propargylic alcohols using LB-ADH. NADPH regeneration was performed using 2-propanol as co-substrate.

An IL (l-butyl-3-meffiylimidazolium benzene sulfonate [BMIm][PhS03]) has also been used as a reaction medium for the synthesis of a-methylene CCs from C02 and propargyl alcohols, using transition metal salts as the catalyst (Equation 7.23) [217]. 

Carbonyl compounds have been alkynylated to give the corresponding propargyl alcohols, using TMS-alkynes and a base such as acetate or phenoxide ion.193... 

A highly efficient synthesis of l-alkylidene-l,3-dihydrobenzo[f]furans from t>-hydroxymethyl iodoarenes and propargyl alcohols uses a bimetallic Pd/Cu-catalyzed Sonogashira coupling/cyclization reaction (Equation 132) <1999SL456>. Pd/l,4-bis(diphenylphosphino)butane (DPPB)-catalyzed reaction of t>-allylphenols under a CO atmosphere leads to carbonylative cyclization to form benzannulated lactones <2006ASC1855>. A similar carbonylative cyclization leads to the stereoselective formation of 3-alkenyl phthalides <2006T4563>. 

An interesting stereospecific 1,2-shift is observed upon treatment of complex (163) with trimethyl aluminium and a nucleophile (Scheme 237). Direct fluorination of chiral-complexed propargylic alcohols using DAST can be achieved in good diastereomeric excess (Scheme 238). 

Alkynic ketones have been used extensively in natural product synthesis, due in large part to the contributions of Midland and coworkers and the development of generd methods for enantioselective reduction of this moiety to afford optically active propargyl alcohols using chiral trialkylboranes. Furthermore, the derived alkynic alcohol is a versatile system which can be manipulated directly into cis-or rra 5-allylic alcohols and as a precursor for vinylorganometallic species. This section will briefly cover progress made in the direct acylation of alkynic organolithiums with the acylation protocol d veloped by Weinreb (see also Section 1.13.2.7). 

In the laboratory of E.J. Corey, the first synthesis of nicandrenones (NIC), a structurally complex steroid-derived family of natural products, was accomplished. The side chain of NIC-1 was constructed from the known six-membered lactone which was converted to the Weinreb s amide by treating it with excess MeNH(OMe) HCI and trimethyl-aluminum. The resulting primary alcohol was protected as the TBS ether. The ethynylation of this amide was carried out by reaction with two equivalents of lithium trimethylsilylacetylide to afford an ynone, which was reduced enantioselectively to the corresponding propargylic alcohol using CBS reduction. 

Methyl 7-hydroxyhept-5-ynoate is an important precursor to alkylating agents that are used to Introduce the complete prostaglandin a-s1de chain.It is normally prepared from propargyl alcohol using a six-step sequence originally introduced by Corey and Sachdev with subsequent modifications.Alternative routes to methyl 7-hydroxyhept-5-ynoate have also been reported but appear less efficient than the one described here. 

Scheme 8 (a) Catalysed nucleophilic substitution of propargylic alcohols with a range of nucleophiles, and (h) Proposed catalytic cycle for the nucleophilic substitution of propargylic alcohols using the bimetallic Ru thiolate complex (7)... 

Tokunaga and Wakatsuki reported a one-pot indole synthesis from anilines and propargyl alcohols using Rn3(CO)j2 [5], and Nicholas and colleagues reported a Ru-catalyzed indole synthesis via the reductive annulation of nitros-oarenes with alkynes (equation 3) [6, 7]. Saa and coworkers described the Ru-catalyzed cycloisomerization of o-alkynylanihnes (equation 4) [8, 9]. Nissen and Detert reported a total synthesis of lavendamycin that featnred a Ru-catalyzed [2-f2-f2] cycloaddition of an o-alkynyl-ynamide, a method that was superior to rhodium catalysis both in terms of efficiency and regiochemistiy [10]. 

Although multi-component domino reactions under NHC-catalysis are still scarce in the literature, an elegant three-component example allowing the access to highly functionalized dx-e-ketoesters (130) has been documented. " This three-component domino method involves coupling of an enal, a chalcone and propargyl alcohol using... 

Y. Pedduri, J. S. Williamson, Tetrahedron Lett. 2008, 49, 6009-6012. One-pot synthesis of highly snbstituted tetrahy-drofurans from activated propargyl alcohols using Bu P. 

There are a number of approaches to this chemistry, and the conversion of propargyl alcohols using TCCA as the chlorinating agent in methanol/water is a practical method [64]... 

Scheme 3.24 Synthesis of a,P-unsaturated amides from propargylic alcohols using hydroxylamine as nitrogen source...

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