PROPIOLALDEHYDE, DIETHYL ACETAL

ALKYNES VIA PHASE TRANSFER-CATALYZED DEHYDROHALOGENATION PROPIOLALDEHYDE DIETHYL ACETAL... 

Propiolaldehyde diethyl acetal has found numerous synthetic applications in the literature which may be briefly summarized. The compound has been utilized in the synthesis of unsaturated and polyunsaturated acetals and aldehydes by alkylation of metal-lated derivatives, " by Cadiot-Chodkiewicz coupling with halo acetylenes, " and by reaction with organocuprates. Syntheses of heterocyclic compounds including pyrazoles, isoxazoles, triazoles, and pyrimidines have employed this three-carbon building block. Propiolaldehyde diethyl acetal has also been put to use in the synthesis of such natural products as polyacetylenes " and steroids. ... 

With monosubstituted acetylenes, such as phenylacetylene (94) and propiolaldehyde diethyl acetal (95), the orientation of phenyl azide is determined both by electronic and steric effects.307 08... 

Potassium hydroxide, 20, 239, 303-304 Potassium persulfate, 274 Potassium superoxide, 304-307 Potassium tri-sec-butylborohydride, 307 Prins reaction, 159 Progesterone, 107 Proline, 10, 307 1,3-Propanediol, 37 Propargylic alcohols, 8, 53 Propargylic chlorides, 155 (E)-Propenyllithium, 141 Propiolaldehyde diethyl acetal, 79-80 Propiolamidium salts, 124 Fropiolate esters, 8 Propiolic add, 295 Propylene carbonate, 74 Propylene oxide, 74 Protolichesterinic add, 412 Pterocarpins, 114 Pulegone, 287, 288, 308-309 tosylhydrazones, 375-376 Pulvinic acid pigments, 291 Pumiliotoxin, 28... 

Tyrrell demonstrated a three step tandem sequence involving an intermolecular Nicholas reaction, intramolecular Nicholas reaction, and a cationic cyclization. Treatment of silyl enol ether 55 with hexacarbonyl(propiolaldehyde diethyl acetal) dicobalt and boron trifluoride provides cobalt-alkyne complex 56. Exposure of this material to tetrafluoroboric acid promotes an intramolecular Nicholas reaction to form the second six-membered ring. Alkyne decomplexation with ceric ammonium nitrate enables the final cyclization step to yield the target tricycle 57." ... 

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. ... 

Propiolaldehyde, 3-chloro-, diethyl acetal (8) 1-Propyne, 1-chloro-3,3-diethoxy- (9) (62761-29-9)... 

PHENYLPROPARGYL ALDEHYDE DIETHYL ACETAL (Propiolaldehyde, phenyl-, diethyl acetal)... 

Propargyl alcohol, 36, 67 Propiolaldehyde, 36, 66 phenyl-, diethyl acetal, 39, 59 Propionic acid, /3,/3 -thiodi-, dimethyl ester, 30, 65 Propionic anhydride, 37, 60 Propionitrile, 30, 51 Propionitrile, /3-anilino-, 36, 6... 

The challenge of the synthesis of the ene-diyene natural products was one of the factors that brought the Sonogashira reaction to prominence. Three Sonogashira reactions were used in a synthesis of the core of the esperamycin/calichemicin anti-tumour agents (Scheme 2.117). Two were employed in sequence to add two alkynes onto cw-l,2-dichloroethylene 2375 to form the ene-diyne 2376. Due to the sensitivity of propiolaldehyde, its diethyl acetal was employed. After hydrolysis of the acetal, a diene unit was installed. 

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