Cyclopropanone ethyl hemiacetal

Cyclopropanone ethyl hemiacetal was first synthesized by the reaction of ketene and diazomethane 1n ether at -78°C in the presence of ethanol.4 The yield is low (43%) and the reaction 1s hazardous, especially when a large-scale reaction is required. The method described in this procedure for the preparation of cyclopropanone ethyl hemiacetal from ethyl 3-chloropropanoate... 

Cyclopropanone ethyl hemiacetal is a molecule of considerable interest since its reactions appear to involve the formation of the labile cyclopropanone.7 It readily undergoes nucleophilic addition of Grignard reagents,4,5 azides,4 and amines5 to provide 1-substituted cyclopropanols in high yields. It has been reported that upon treatment with an equimolar amount of methylmagneslum iodide, the cyclopropanone ethyl hemiacetal is... 

Cyclopropanone ethyl hemiacetal Cyclopropanol, 1-ethoxy- (8,9) (13837-45-1) 1-Ethoxy-l-triuiethylslloxycyclopropane Silane, [(l-ethoxycyclopropyl)oxy]-... 

CYCLOPROPANONE ETHYL HEMIACETAL FROM ETHYL 3-CHLOROPROPANOATE... 

Reaction of cyclopropanone ethyl hemiacetal with methylmagnesium bromide and two equivalents of cyclohexanone lithium enolate provides a very interesting and highly stereospecific synthesis of tricyclic cycloheptanones a serendipitous reaction... 

The ethyl hemiacetal of cyclopropanone (152) reacts with sodium azide in buffered acetone (KH2P04 Na0H) to form a ) -lactam (153) (equation 106) . 

The preparation of cyclopropanones by photochemical decarbonylation 8-i°) js illustrated by the formation of 1-ethoxycyclopropanol from the photolysis of tetramethylcyclobutane-l,3-dione (17) in ethanol.9 a> As shown in Scheme 4, the desired hemiacetal is accompanied by a number of side products including ethyl isobutyrate which results from the... 

Other hemiacetals which have been prepared include the methyl 8<9a>, ethyl 9b), and isopropyl hemiacetals 81) of tetramethylcyclopropanone, the phenyl, a- and (3-naphthyl hemiacetals of cyclopropanone 82>, and the benzyl hemiacetal of 2,3-di-f-butylcyclopropanone. 13> In the last case, the benzylic methylene protons display an AB pattern in the PMR spectrum indicating that the two Ybutyl groups are trans to one another. Although derivatization of this di-f-butyl ketone was possible, carbonyl addition may be hindered by steric factors as suggested by the lack of reaction of 2,2-diY-butylcyclopropanone with methanol. 55a>... 

Cyclopropanone acetals require far more vigorous conditions (concentrated acid and heating) for ring cleavage compared to hemiacetals. As shown in Scheme 28, the reaction may proceed in two directions, one involving O-protonation (a) and the other C-protonation (b). In the case of 1,1-diethoxycyclopropane where both paths are competitive, refluxing hydrochloric acid yields both chloroacetone and ethyl propionate (Table 17).25)... 

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