Acetylenic esters structure

Soon after the 1946 report by Woodward on the condensation of thioglycolic acid and a,P-unsaturated esters in the presence of base to produce structures like 2-carbomethoxy-3-ketotetrahydrothiophene 4, Fiesselmann extended this reaction to a,p-acetylenic esters for the direct preparation of 3-hydroxy-2-thiophenecarboxyIic acid derivatives. ... 

Dihydronaphthalen-1,4-iwmes from Isoindoles The naphthalen-l,4-imine derivatives 91-99 have been obtained by addition of acetylenedicarboxylic esters to the appropriate isoindoles. 3- ss Some such adducts react further with acetylenic esters (see Sections III, G and H), so that A -ethyl- and A-n-butylisoindole give 1 2 adducts with dimethyl aoetylenedicarboxylate instead. iV-Methylisoindole appears to be exceptional in giving an oily 2 1 adduct, for which structure (100) was suggested on analogy with the 2 1 adduct obtained from l,3-diphenylbenz[c]furan and acetylenedicarboxylic acid. ... 

The reaction of thiourea with acetylenic esters has been variously reported to give a thiazolin-4-one (372), an imidazolinethione (373), or a l,3-thiazin-4-one (374) " derivative. However, recent studies have shown that in fact it is the thiazolin-4-one (372) that is formed in this reaction [Eq. (55)]. In the light of this observation, it may now be necessary to revise the structures of products obtained from the reaction of A -methylthiourea, M -dimethylthiourea, and thiosemicarbazides with acetylenic esters. The reaction of a thiourea derivative such as A(-thiocarbamoylpiperidine with DMAD is reported to give 5-(carbomethoxymethylene)-2-piperidino-A -1,3-thiazolin-4-one (375) [Eq. (56)]. °... 

Addition of DMAD to substituted 2-azidobenzoxazoles (e.g., 21) is stated483 to give triazoles (e.g., 22), which are described as anthelmintics and nematocides. With 2-aminobenzoxazole (23), DMAD and other acetylenic esters are reported484 to give the products 24, although isomeric structures seem equally possible. 

The addition of DMAD to 2-aminothiazole (25) gave 26, whereas propiolic ester gave 27, 28 and 29, all derived by Michael-type additions.549 Dunwell and Evans550,551 have also added acetylenic esters to 2-amino- (and 2-amino-4-methyl)thiazole and obtained 26 and 27 from DMAD and EP, and similar compounds from tetrolic and phenyl-propiolic esters. By independent synthesis, these compounds were shown not to have the isomeric structures derived by initial addition to the exocyclic nitrogen. 

The reaction of vinylthiophenes with acetylenic esters has been studied in detail. Although the overall yields were not generally good, structure determinations were carried out even on minor compounds obtained in very low yield. 

Photoaddition of dimethyl acetylenedicarboxylate to cis- and trans-but-2-enes gives four [(76), (77), (78), and (79) E = C02Me] of the seven possible bicyclic products. The structures of the adducts were established by 220 MHz n.m.r. spectroscopy and by consideration of the symmetry properties of the molecules. The acetylenic ester is the excited partner in the addition. Under the conditions described, no mono-adducts could be detected in the products. 

The conjugate addition of trialkylstannyl copper reagents to a,/3-acetylenic esters or /3-substituted acrylates, leads to the stereoselective preparation of potentially useful stannyl acrylates. The stereochemical course of the conjugate addition to a,/3-acetylenic esters was shown to be dependent on the constitution of the reagent and upon the structure of the substrate. ... 

Rearrangement of acetylenic sulphenates to the allenic sulphoxides 151 was discovered when the synthesis of propargylic ester of trichloromethanesulphenic acid 152 was attempted (equation 86). This reaction is of general scope and gives very good yields of allenic sulphoxides (Table 14) from structurally diverse cohols and various sulphenyl chlorides Reaction of alkynols 153 with benzenesulphenyl chloride in the presence... 

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