Ethenyl group

The additional coupling (9.8 Hz) of the cyclopropane proton A at <5// = 1.60 is the result of a vicinal H atom in the side-chain. This contains a methyl group B, a vinyl group C and an additional substituted ethenyl group D, as may be seen from the one dimensional H and C NMR spectra and from the CH COSY diagram. 

KMn04, acetone, H2O, 0°, 10 min, 78-90% yield. These conditions are used for the related ethenyl group. 

Inner-outer-ring dienes are very useful in the synthesis of polycyclic molecules. Their reactivity in the Diels-Alder reaction depends on the type of ring (carbo-cyclic, heterocyclic, aromatic) that bears the ethenyl group or on the electronic effects of substituents at the diene moiety [30]. 

Name substituent groups as in alkanes, indicating their locations by the number of the main-chain carbon to which they are attached. The ethenyl group and the propenyl group are usually called the vinyl group and the allyl group, respectively. 

The full account has appeared " of the synthesis of the A °-marine steroid (284). In addition the isolation and synthesis of the related 3iS-hydroxy-A -compound (285) " and the lla-hydroxy-3-oxo-A -compound (286) were reported. In the synthesis of (286) the 17/3-ethenyl group was constructed through exhaustive methylation of the 20-amino-compound followed by Hofmann elimination. Epimerization of pregnenolone at C-17 led to the synthesis of a number of 20-methyl-17a-pregnanes. Syntheses have been reported for the four isomeric 3,ll-diamino-5a-pregnanes, and the 6,19-dimethoxy-3,5-cyclopregnan-20-one (287) was synthesized in model experiments aimed at a strophanthidin synthesis. ... 

Formation by a radical addition reaction The presence of methyl and ethenyl groups in the products indicates that shock waves destroyed the structure of benzene and formed some lower-molecular-weight radicals (e.g., methyl and ethenyl radicals). If we assume Uiat the formation of a MeNap or PhNap molecule is a result of attack by a methyl or a phenyl radical against naphthalene molecule, respectively, the yield relations in isomers estimated from tire reactivity indices would be 1-MeNap >2-MeNap and 1-PhNap >2-PhNap. These relative amounts are inconsistent with Uiose of the shock products. Therefore, it is unreasonable to invoke a radical reaction only for the reaction of MeBip and PhNap. 

We have recently converted the ethenyl group of the cinchona alkaloid into an ethynyl group by a bromination-double-dehydrobromination sequence [17, 18]. Bromina-tion of the natural products 1, 2 in CC14 provided the corresponding 10,11-dibromo-cinchona alkaloids in quantitative yield as a yellowish precipitate. The double dehydrobromination to afford alkynes 26 and 27 was studied under a variety of... 

Functionalization of indole derivatives can be achieved by this couphng procedure. Subsequent incorporation of ethenyl group and 1,2-dihydroxylation furnished the -carboline alkaloids (/ )-(-)-pyridiridols (Scheme 12.97) [199]. 

The highly diastereoselective cyclopropanation of an a.jS-dehydroamino acid derivative bearing a (lS)-l,2-dioxolane group as inducing substituent is achieved by treatment with diazomethanc followed by photolysis. The chiral substituent is transformed into an ethenyl group, thus allowing synthesis of an enantiomerically pure (lS,27 )-l-amino-2-ethenylcyclo-propanecarboxylate derivative103. 

Syntheses have been reported for the A °-marine steroids (305) and (306). The introduction of the 17/8-ethenyl group, which is an unusual feature, was achieved by reaction of the tosylhydrazone of a 20-oxo-derivative with Bu"Li " or by reaction of the ethylenethioacetal of a 20-oxo-derivative with deactivated Raney nickel. 

Reactions between the diesters or dichlorides of (alka-l,2-dienyl)phosphonic acids with additional ethenyl groups at or at (pentatrienyl phosphonic acids) and... 

---