Triethyl orthopropionate

Imidazo[4,5- ]pyridines 117 <2003BML2485>, 118 <2004BML3165>, 119 <2005BML2129>, and 120 <2003BML289> have been prepared from the corresponding diaminopyridine and the appropriate trialkyl ortho-formate or, in the case of 120, triethyl orthopropionate. However, in each case, the authors fail to report product yields. 

In the ortho ester Claiscn rearrangements of phenylsulfanyl-substituted allylic alcohols 11, the Z-isomer of product 12 is formed predominantly, but not always exclusively (Table 17).30 When triethyl orthopropionate (R2 = Me) is used, the diastcrcoselectivity is good to excellent with ( )-allylic alcohols 11, whereas the Z-isomer of 11a gives almost a 1 1 mixture. The stereochemical results were discussed on the basis of transition-state models.30... 

Fig. 40. Release of lysozyme from a polymer prepared from 1,2,6-hexanetriol and triethyl orthopropionate at pH 7.4 and room temperature. Molecular weights are as indicated. ( ) 3200 ( ) 4600...

In a similar manner, 1,1,4-cyclohexanetrimethanol (3.524 g, 20 mmol) was allowed to react with triethyl orthopropionate (3.634 g, 20 mmol). This reaction produced a polymer which remained in the cyclohexane solution. Precipitation into methanol yielded a polymer having a MW of 51 000 (GPC using polystyrene standards) and a Tg of 67.8 °C. The polymer was soluble in organic solvents with low or medium polarities such as methylene chloride, chloroform, ether, tetrahydrofuran and ethyl acetate. 

In order to acquire a set of spectral data allowing the assignment of configuration at C-24 and C-25 of 24-methyl-26-hydroxysteroids, model compounds with all possible configurations at C-24 and C-25 were synthesized by a scheme involving a Claisen rearrangement reaction on cA-allylic C-22 alcohols (80) (Fig. 20). These were converted, by reaction with triethyl-orthopropionate, into a... 

In a synthesis of ( )-geijerone 119 and ( )-y-elemene 120, orthoester rearrangement has been used by Kim [27]. Condensation of triethyl orthopropionate with primary allylic alcohol 121 afforded the rearranged ester 122 as a 1 1 mixture of diastereomers. Here the diastereoselectivity at C-3and C-4is controlled in a further stage during cyclization affording compound 123 (Scheme 6.16). 

One of the key steps in the stereoselective synthesis of the HMG-CoA reductase inhibitor mevilonin 208 described by Wovkuhch and Uskokovic [45] involved a Claisen-Johnson rearrangement Accordingly, aUyUc alcohol 210 prepared in few steps from (S)-pulegone 209 gave rise, after condensation with triethyl orthopropionate, to ester 211 as a 89/11 mixture of diastereomers (Scheme 6.32). 

Triethyl orthopropionate refluxed ca. 4 hrs. with morpholine in the presence of p-toluenesulfonyl chloride with slow distillation of the alcohol formed 1,1-dimorpholino-l-propene. Y 78.5%. F. e. s. H. Baganz and L. Domaschke, B. 95, 2095 (1962). 

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