Propargyl alcohol derivative

Eventually, indole acetic acid 2 was prepared from iodoaniline 28 and propargyl alcohol derivative 61 via the newly developed coupling reaction followed by a cyanide displacement-hydrolysis sequence, as shown in Scheme 4.16. 

A three-component, one-pot reaction of acyl chloride, propargylic alcohol derivatives and Nal using palladium as catalyst provided trisubstituted furans as depicted in the following scheme <06EJOC2991>. 3-Chloro-4-iodofurans can also be produced when IC1 and NaCl are used in the second step. 

Scheme 63 Mn-catalyzed allylmagnesation, alkylmagnesation, and phenylmagnesation of homopropargyl and propargyl alcohol derivatives as well as allenes.

An important variant for transition metal-catalyzed carbon-nitrogen bond formation is allylic substitution (for reviews, see1,la lh). Nucleophilic attack by an amine on an 7r-allyl intermediate, generated from either an allylic alcohol derivative,2 16,16a 16f an alkenyloxirane,17-19,19a-19d an alkenylaziridine19,19a 19d, or a propargyl alcohol derivative,21,21a 21d gives an allylic amine derivative. 

Organocopper-Mediated Alkylation of Propargyl Alcohol Derivatives... 

The formation of chiral allenes from centrochiral propargylic alcohol derivatives and organocopper reagents, e.g., the conversion of (/ )-l-cthynylpentyl acetate to allene 928. 

Cyclic carbonates have also been synthesized from propargylic alcohol derivatives and C02 as the starting materials. This synthetic approach (Equation 7.22) is based on cyclization of the propargylic carbonate moiety (HC=CCH20C02-) into the corresponding a-alkylidene CC, in the presence of a suitable catalyst such as ruthenium [202], cobalt [203], palladium [204, 205], copper [206-211], or phosphine [212-214],... 

Although acyloxy, phosphatyloxy, and tosyl allenones were obtained from the corresponding propargyl alcohol derivatives via silver catalysis through an overall process that resembled [3,3]-sigmatropic rearrangement (see Sections 3.41 and 3.43), the mechanism was not fully proved and is still in question. 

Thiolate-bridged diruthenium complexes such as Cp RuCl(p2-SR)2RuCp Cl catalyze the propargylic substitution reaction of propargylic alcohol derivatives with various carbon-centered nucleophiles [118-120]. Ketones [119] (Eq. 88), aromatic compounds [120] (Eq. 89), or alkenes thus selectively afford the corresponding propargylated products with C-C bond formation. An allenylidene intermediate is proposed in these reactions. They are detailed in the chapter Ruthenium Vinylidenes and Allenylidenes in Catalysis of this volume. 

A new preparative method for allylic indium(m) reagents via a reductive transmetallation of 7r-allylpalladium(n) or 7T-allylnickel(n) complexes with indium(i) salts is reported. This method enables the use of a wide variety of allylic compounds, such as allylic chlorides, acetates, and even allylic alcohols, in combination with Pd or Ni catalysts.43-50 7r-Allylpalladium(ii) resulting from the addition of arylpalladium(n) to allene is also transformed by metallic indium to the corresponding allylindium.51-54 Similarly, propargylindium(m) can be prepared from the corresponding propargyl alcohol derivatives.55-58... 

In this synthesis (Scheme 6), the C2-symmetri-cal triacetonide of D-mannitol (32) is converted via the epoxide 33 and its nucleophilic addition product 34 to the propargylic alcohol derivative 35. From this intermediate, the Z-configured vinyl iodide 36 is stereoselectively obtained by hydroalumination/iodination. The Pd-catalyzed Heck cyclization then affords the isomerically pure product 37, which represents a potential building block for the synthesis of la,2y5,25-trihy-droxy-vitamin D, following the classical Wittig strategy of Lythgoe. 

A mechanistically relevant dimerization of the propargyl alcohol derivative 69 resulting in 70 was also promoted by a cationic complex 68 (Scheme 4.25) [58]. The reaction was considered to start with the regioselective formation of the ruthena-cyclopentadiene 71 from 68 and 69, and the subsequent migration of the hydroxy... 

In contrast to these linear couplings of propargyl alcohol derivatives, a three-component cyclo-coupling of 72 proceeded in the presence of 17 and acetic acid to give rise to an alkylidenecyclobutene 73 in 66% yield (Scheme 4.27) [61]. The four-mem-bered ring skeleton vas considered to be derived from the ruthenium(II) cyclobutadiene complex, vhich might be formed via the corresponding ruthenacyclopenta-diene. 

Low-valent titanium alkoxide complexes have proved to be particularly useful in intramolecular nucleophilic acyl substitution (INAS) reactions. Addition of propargyl alcohol derivatives to 236 has been used as an efficient and practical method for the synthesis of allenyltitanium compounds (Scheme 43).197 Performing the reaction with a homopropargylic carbonate provides access to an alkenyltitanium compound with a lactone moiety.198 This methodology has since been extended to include olefinic carbonates and, through trapping with appropriate electrophiles such as aldehydes and iodine, affords substituted lactones.199... 

Enantio-enriched axially chiral allenyltitanium compounds have been synthesized from optically active propargyl alcohol derivatives by the reaction with a divalent titanium reagent, TKOPfj MgXPr1, and their reactions with a variety of electrophiles have been studied.285... 

Even the propargylic alcohol derivative 35 with an electronically almost unactivated triple bond smoothly undergoes palladium(0)-catalyzed cycloisomerization to give an 85% yield of the allylic alcohol, (3/ , 3a5 )-3-cyclohexyl-4-methylene-3,3a,4,5-tetrahydro-lff-cyclo-penta[c]furan-6-methanol (36)." The substrate molecule containing a rer/-butyldimethylsilyl substituent at the alkyne instead of a hydroxymethyl group, however, again failed to undergo the cycloisomerization, presumably due to steric hindrance. ... 

As shown below, cross-coupling of add chlorides with THP-protected propargyl alcohol derivatives gave rise to the corresponding alkynone, which underwent acid-assisted electrophilic addition of hydrogen halide with concomitant deprotection and cyclization, affording 3-halofurans. If RB(OH)2 was added into the reaction system before work-up, the reaction can provide Suzuki-coupled products in moderate yields. 

The reactivity of allenylpalladium species, derived from oxidative addition of propargyl alcohol derivatives to palladium (0), has attracted considerable attention in organic synthesis.283 Recently, the intramolecular reaction of the propargylic derivatives 665 with an oxygen and nitrogen nucleophile has been widely utilized for the synthesis of heterocyclic compounds. The key step of formation of a heterocyclic ring is intramolecular nucleophilic attack of a... 

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