Nucleophilic substitution of vinylic halogens in 3-halomethacrylonitriles. Some observations on olefin stabilities

Abstract

3-Chloro-and 3-bromomethacrylonitrile (E-and Z-) have been shown to undergo nucleophilic substitution at C-3 with > 9 5 % retention of configuration. The configuration of each product has been established by the use of nuclear magnetic resonance spectroscopy. The thermodynamic position of equilibrium for each pair of E-Z isomers has been determined and the factors which affect this equilibrium are discussed. Some form of cis interactions, non-steric in origin, dominates in determining the equilibrium positions.

New stereoselective synthesis of 9-methyl-cis-decalin derivatives by double Michael reaction of 3-methyl-4-methylenecyclohex-2-enone and its congeners with dimethyl 3-oxoglutarate

“…In order to extend the applicability of the new annulation reaction to construction of the cis-decalin system, the dienone (13) was prepared. The dimethylcyclohexenone ester (14) has been prepared from Hagemann's ester by Ananthanarayan and Sorensen.'…”

“…However, the Acetalisation of the ester ( 14) with ethylene glycol in benzene in the presence of toluene-9-sulphonic acid with azeotropic removal of water gave a mixture of the acetals (16) (isomeric with respect to the position of the double bond, revealed by gas chromatography-mass spectroscopy). Reduction of the mixture with lithium aluminium hydride in ether, followed by acid hydrolysis with dilute hydrochloric acid, furnished the dienone (13) in 40% yield from the cyclohexenone ester ( 14) as a result of hydrolysis of the acetal group and concomitant dehydration of the primary alcohol group.…”

“…Regioselectivity of the cycloaddition rested on the investigation of Ibuka and his coworkers.12 Acetalisation of the keto-ester (27) gave the acetal (28), which was submitted to reduction with lithium aluminium hydride in ether followed by hydrolysis with dilute hydrochloric acid in acetic acid to give a mixture of the keto-alcohol (29) and the dienone (30) in 60 and 35% yield, respectively, both being separable in pure form by column chromatography with silica gel in chloroform. Attempts to convert the alcohol (29) into the dienone (30) with several kinds of acids and under forcing conditions was unsuccessful, in contrast to the preparation of dienones (l), (2), and (13). Tosylation of the alcohol (29) in the usual manner gave the tosylate (31) and the chloride (32) in 60 and 21% yield, respectively.…”

Liquid Bismuth Calorimetry: Enthalpies of Solution of Copper, Indium, and Tellurium, and Enthalpies of Formation of Cuprous Selenides

“…The data thus obtained were used to calculate the expected equilibrium position for 15 trisubstituted isomer pairs, and comparison between calculated and observed data for the six available isomer pairs was good. In an earlier paper (1) we found evidence to suggest that the position of a cis-trans equilibrium for a trisubstituted olefin could be estimated by adding the contribution of the isolated vicinal pairs of substituents. Thus by using the fact that the equilibrium position recorded for 3-chloroacrylonitrile is 69% cis (2) and for I-chloropropene is 75.5% cis (2) we can estimate that the percentage of the E form of 3-chloromethacrylonitrile should be 58% (1) (31169 x 75.5124.5 = 58/42).…”

C-nucleoside antibiotics. 2. Synthesis of oxazinomycin (minimycin)

“…Upon aqueous workup of the reaction mixture, 10,Il -----14 13 1 TFA / HzO 1 0 1 I S some starting material is regenerated, presumably arising from the carbonylation product of that portion of enolized 12 which has E geometry. Both of these are characterized At this point, this seemingly circuitous sequence makes available the proper functionalities for the final steps of the oxazinomycin synthesis, without having required prohibitively harsh (basic) solvolysis conditions.…”