Two new isoflavanoids from <i>bolusanthus speciosus</i>

The structures of two new isoflavonoids from the combined ethyl acetate/methanolic extracts of the stem bark of Bolusanthus speciosus have been established as 4,7,2' -trihydroxy-4' -methoxyisoflavanol (1) and 5,7,3',4' -tetrahydroxy-5' -(2-epoxy-3-methylbutyl)isoflavanone (2). Five other known isoflavonoids, 5,7,3' -trihydroxy-4' -methoxy-5' -γγ; -dimethylallylisoflavanone, 5,7,2' -trihydroxy-4' -methoxy-6,5' -di)(γγ -dimethylallyl)isoflavanone, 5,7,2' ,4'-tetrahydroxy-8,5'2; -di(γγ -dimethylallyl)flavanone, 5,7,2',4' -tetrahydroxy-8,3' -di(γγ -dimethylallyl)-isoflavanone, and derrone were also isolated. Compound 2 showed moderate activity against gram positive bacteria and weak activity against gram negative bacteria, while compound 1 was weakly active against both organisms in a TLC bioautography assay

Chemical constituents of the root wood of Erythrina sacleuxii and determination of the absolute configuration of suberectin

Phytochemical investigation on the root wood of Erythrina sacleuxii (Leguminosae) led to the isolation of nine secondary metabolites (1-9). Compound 1 was isolated from the genus Erythrina for the first time. The pure compounds were identified on the basis of comprehensive spectroscopic and spectrometric analyses, while their absolute configurations were determined based on chiroptical measurements. Compounds 5 and 6 showed weak antifungal activity against Pyricularia oryzae with MIC values of 20&nbsp;µg/mL. &nbsp; Bull. Chem. Soc. Ethiop. 2020, 34(1), 135-140. DOI: https://dx.doi.org/10.4314/bcse.v34i1.1

One-step synthesis and exploratory chemistry of [5]dendralene

(Chemical Equation Presented) Complex polycycles made simple: A practical synthesis of the simplest cross-conjugated pentaene, [5]dendralene, is reported. The hydrocarbon undergoes controllable and atom-efficient domino sequences (see scheme) to generat

Practical synthesis of the dendralene family reveals alternation in behavior

Back from obscurity: The practical synthesis of the first six members of the fundamental class of acyclic branched oligoalkenes has been achieved. The syntheses allow access to the target compounds on multigram scales in good yields. Members of the family with even numbers of double bonds are significantly more stable than those with odd numbers (see picture), and exhibit different chemical reactivities in Diels-Alder reactions

Nitroso-dienophile additions to dendralenes: A short synthesis of branched aminosugars

The first heteroatom-based dienophile cycloadditions to cross-conjugated alkenes ([n]dendralenes) are reported. Nitroso-dienophiles undergo smooth single and double Diels-Alder additions to the parent dendralenes with orientational regio- and stereoselectivity and, notably, with reactivity that depends upon the parity of the [n]dendralene. The first crystal structure of a cross-conjugated hexaene is reported. Vasellas nitroso-sugar reagent gives a highly enantiomerically enriched double cycloadduct with [3]dendralene. This bicyclic oxazine is successively dihydroxylated and then ring-opened to form a branched chain diamino tetrol

Domino cycloaddition organocascades of dendralenes

Hooray Horeau! Highly enantioselective organocatalyzed Diels-Alder reaction cascades are disclosed for the first time. The reaction enables the efficient and rapid construction of enantiopure polycycles from simple achiral, acyclic polyenes

Nitroso-Dienophile Additions to Dendralenes: A Short Synthesis of Branched Aminosugars

The first heteroatom-based dienophile cycloadditions to cross-conjugated alkenes ([<i>n</i>]dendralenes) are reported. Nitroso-dienophiles undergo smooth single and double Diels–Alder additions to the parent dendralenes with orientational regio- and stereoselectivity and, notably, with reactivity that depends upon the parity of the [<i>n</i>]dendralene. The first crystal structure of a cross-conjugated hexaene is reported. Vasella’s nitroso-sugar reagent gives a highly enantiomerically enriched double cycloadduct with [3]dendralene. This bicyclic oxazine is successively dihydroxylated and then ring-opened to form a branched chain diamino tetrol

Nitroso-Dienophile Additions to Dendralenes: A Short Synthesis of Branched Aminosugars

The first heteroatom-based dienophile cycloadditions to cross-conjugated alkenes ([<i>n</i>]dendralenes) are reported. Nitroso-dienophiles undergo smooth single and double Diels–Alder additions to the parent dendralenes with orientational regio- and stereoselectivity and, notably, with reactivity that depends upon the parity of the [<i>n</i>]dendralene. The first crystal structure of a cross-conjugated hexaene is reported. Vasella’s nitroso-sugar reagent gives a highly enantiomerically enriched double cycloadduct with [3]dendralene. This bicyclic oxazine is successively dihydroxylated and then ring-opened to form a branched chain diamino tetrol

Nitroso-Dienophile Additions to Dendralenes: A Short Synthesis of Branched Aminosugars

The first heteroatom-based dienophile cycloadditions to cross-conjugated alkenes ([<i>n</i>]dendralenes) are reported. Nitroso-dienophiles undergo smooth single and double Diels–Alder additions to the parent dendralenes with orientational regio- and stereoselectivity and, notably, with reactivity that depends upon the parity of the [<i>n</i>]dendralene. The first crystal structure of a cross-conjugated hexaene is reported. Vasella’s nitroso-sugar reagent gives a highly enantiomerically enriched double cycloadduct with [3]dendralene. This bicyclic oxazine is successively dihydroxylated and then ring-opened to form a branched chain diamino tetrol