Reaction of certain geometrically defined 1,1-dioxy-4-alkyl- and -4,4-dialkyl-substituted buta-1,3-dienes with halogenated quinones does not involve Diels-Alder or Michael addition chemistry. Instead, rapid competitive oxidation of the dienes to give 2,4-dienoate esters was observed. This new reaction involves strong spatial association between diene and quinone, hydrogen being transferred specifically from the (4E)-alkyl group. Its scope is compared with addition of the same terminally substituted dienes towards the reactive non-quinonoid dienophile tetracyanoethylene.
Esterification of the trienoic acid with o-xylylene dibromide gave the bis ester that underwent a templated Diels−Alder reaction to afford the macrodiolide stereospecifically in a single step. The synthesis of bistellettadine A was completed in four steps by hydrolysis and side chain elaboration.
Synthesis and1H-,13C-, and57Fe-NMR spectra of mono- and bis[tricarbonyl(?4-diene)iron], and (?3-allyl)tetracarbonyliron trifluoroborate complexes
作者:Christoph M. Adams、Giovanni Cerioni、Andreas Hafner、Hermann Kalchhauser、Wolfgang von Philipsborn、Roland Prewo、Andreas Schwenk
DOI:10.1002/hlca.19880710526
日期:1988.8.10
with a (Z)-configuration terminal Me group show steric inhibition of metal complexation resulting in lower yields and formation of tetracarbonyl(η2-diene) and tricarbonyl(η4-heterodiene) complexes as additional products. Regioselective attack by C-nucleophiles at the carbonyl C-atoms of the functional group with or without concomitant 1,3 mogration of the Fe(CO)3 group was used to synthesize polyenes and
Catalytic Regioselective γ-Methylenation of α,β-Unsaturated Aldehydes Using Formaldehyde via Vinylogous Aldol Condensation
作者:Mahesh S. Kutwal、Sachin Dev、Chandrakumar Appayee
DOI:10.1021/acs.orglett.8b04110
日期:2019.4.19
first vinylogous aldol condensation of α,β-unsaturated aldehydes using aqueous formaldehyde is developed under mild reaction conditions to form the γ-methylenated products with excellent regioselectivity. Using this methodology, a short synthesis of α-triticene, an antifungal compound, is achieved in two steps. The practicality of this methodology is demonstrated by the gram-scale synthesis. Formation of
Addition of sodium derivatives of allyl alcohols (2) to phenylthioacetylene (1) forms adducts (3) which on oxidation and pyrolysis undergo Claisen rearrangement and elimination of benzenesulphenic acid to yield the 2,4-dienals (6).