Prop-2-ynols

First example for the isomerization of propargylic alcohols to isolable a,(3-enals was reported in 1989. A variety of prop-2-ynols can be isomerized to a,/3-unsaturated aldehydes in the presence of a catalytic amount of RuCl2(PPh3)3/ Pr 3P (Scheme 53).92... 

The addition of secondary phosphines H PR2 to prop-2-ynols in the presence of RuCl (C5Me5)(cod) or RuCl(C5Me5)(PPh3)2 provides the first regio- and stereo-selective direct hydrophosphination of propargylic alcohols and leads to bifunctional... 

The ability of the binuclear complex [Cp RuCl(p2-SR)2RuCl(Cp )] to generate cationic allenylidene complexes by activation of terminal prop-2-ynols in the presence of NH4BF4 as a chloride abstractor opens the way to a variety of catalytic transformations of propargylic alcohols involving nucleophilic addition at the Cy atom of the ruthenium allenylidene intermediate (Scheme 19). This leads to the formation of a functional ruthenium vinylidene species which tau-tomerizes into an -coordinated alkyne that is removed from the ruthenium centre in the presence of the substrate. 

Oxabenzonorbornenes undergo a Ru-catalysed reaction with prop-2-ynols under mild conditions to give 1-substituted isochromenes (Scheme 18) <06EJO5449>. 

Quinazoline-2,4(l/f,3/f)-dione with prop-2-ynol gives l,3-bis(prop-2-ynyl)quinazoIine-2,4(1/f,3 )-dione under Mitsunobu reaction conditions. ... 

A class of cationic ruthenium allenylidenes, recently reported by Fiirstner and Dixneuf [259, 260], possesses similar high activity at least in RCM and presumably in ROMP. These cationic species are accessible by reaction of (p-cymene) RuCl2(PR3) with a l-prop-2-ynol, preferably with l,l-diphenylprop-2-ynol (Scheme 5.19). 

To a stirred solution of pyrido[2,3-small amounts over a period of 15 min. The addition caused slight warming of the mixture after which it was heated at reflux for 3 h. After cooling and removal of dioxane in vacuo, the syrupy mixture was subjected to successive extraction with toluene/petroleum ether (40 - 60 °C 1 1) such that a major part of the white crystalline Ph sP was left behind. Column chromatography (MeOH/CH2Cl2 1 99) was used for separation, recrystallization (CHCI,) gave colorless plates yield 0.179 g (25%) mp 160—162°C. 

Oxidative aminomercuriation of prop-2-ynol affords a route to... 

If the reaction between prop-2-ynol and PCI3 (3 1 ratio) is carried out in the absence of a tertiary amine, the liberated HCl dealkylates the tris(prop-2-ynyl) phosphite before it is able to undergo rearrangement, and the product is bis(prop-2-ynyl) hydrogenphospho-nate. ... 

There are other reactions which lead from prop-2-ynyl compounds to allenic phospho-nic acid derivatives. The alkylation of diethyl hydrogenphosphonate with 3-bromopropy-ne under phase transfer conditions yields a mixture of diethylpropadienyl- and (prop-l-ynyl)-phosphonates in 85 15 ratio " The action of heat on a mixture of prop-2-ynol and a phosphoramidous ester, (RO)2PNR 2, results in elimination of R 2NH followed by its re-addition to the rearranged residue to afford a dialkyl (2-amino-prop-1-enyl)-phosphonate. ... 

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