Ethano adduct

Racemic -amino acids, namely 3,3-ethano- -alanine (193 a) and its spiro-cyclopropanated analog 193b, have been prepared by simple one-step hydrogenolytic reduction and deprotection of the primary Michael adducts 94 b and 94 d (Scheme 57) [9,21b]. As methyl esters cannot be deprotected under these conditions, only reductive dechlorination and debenzylation was observed for compounds 91t,u (Scheme 57) [7k]. This looks promising for the construction of... 

I IL / Substituted ethano or etheno adducts H N (HNE-dGuo adducts, HNE-dAdo adduci... 

The 4-nitromethy (benzene arises from ipso attack of NOW at the isopropyl-substituted ring carbon. Unlike methyl, the isopropyl group is eliminated rapidly as propene. Can we say that the other products, 3 and 4, arise by direct substitution Evidently not, because nitration at 0° gives two other products, 5 and 6, which must be formed by ipso attack at the inelhyl-heanng carbon. At low temperatures, intermediate ion 7 is attacked by the weakly nucleophilic ethanoate ion to give 5 and 6. Both of these adducts solvolyze rapidly in 78% sulfuric acid to give 3 only ... 

In a similar biochemically oriented vein, several papers were published during 2003 in the journal Chemical Research in Toxicology, representing yet another area of applicability of 3 mm NMR probe capabilities. In the first of these reports, Hankin et al.159 described the results of an investigation into the covalent binding of leukotriene A4 to DNA and RNA. Later in 2003, Blair and co-workers160 reported on the characterization of 2 -deoxycytidine adducts derived from 4-oxo-2-nonenal, a novel lipid peroxidation product. Two of the adducts characterized, Ai and A2, were consistent with substituted ethano-deoxycytidine structures. The third adduct, B, was characterized as a 7-heptanone-etheno-deoxycytidine adduct (78). 

Figure 4 examples of products obtained by aldehyde-induced reactions ethyl-linked catechin dimer (1), ethyl-linked catechin-malvidin-3-glucoside adduct (2), ethanoic acid-linked catechin-dimer (3)... 

Cumulenes, generally regarded as difficult to prepare, can be obtained readily via rDA methods. Al-lenes, the most basic cumulenes, with a wide range of substituents on the allenic carlxm, can be obtained by FVP of anthracenic DA adducts as shown in equation (114). Butatriene (258), the next in the series of cumulenes, has been produced by FVP of a variety of adducts that includes 9,10-ethano-9,10-dihy-droanthracene, " cyclohexyne and fulvene, furan and benzene cycloadducts. Pentatetraene (260), a compound that is stable enough to be purified by GLC at room temperature, has also been obtained by the FVP of vinylallene (259). ... 

Dehydrogenation of enediones. The adduct (1) of 2,3-dimethoxyquinone and 1,3-dimethoxycyclohexa-l,3-diene is converted into the quinone (2) by enoliza-tion with potassium hydrogen carbonate and oxidation with potassium nitroso-disulfonate. The ethano bridge is lost on pyrolysis at 150° to give the tetramethyl ether of spirochrome-B (3).1... 

The regioselective ET-sensitized addition of primary amines has been cleverly employed by Yasuda and co-woikers in the synthesis of isoquinolines and related alkaloids. For example, the DCNB-sensitized photoamination of stilbene with 2-hy-doxypropylamine in an acetonitrile-water solution yields the adduct 98, which is converted to the benzylisoquinoline 99 upon treatment with CFjSOjH, The P-hydroxyl group of ethano-lamine can be replaced with acetal or vinyl groups which also can serve as precursors of the carbocation required for the acid-catalyzed ring-forming reaction. Analogous reaction sequences have been used to convert phenanthrene to aporphines. ... 

Ethano derivative 71a as a naphth[2,3-/ isoindole precursor was prepared in two ways. The DA adduct 73 of 1,4-naphthoquinone and 1,3-cyclohexadiene was reduced with CeCla and NaBH4 and dehydrated under acidic conditions to give l,4-dihydro-l,4-ethanoanthracene (74) [72], The... 

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