Publication

Remote Substituent Effect on the Electrophilic Additions of 1,3-Dienes - Synthesis of (2r)-5-(Acetoxymethyl)-2-Acetyl-1,2,3,4-Tetrahydro-10-Methoxynaphthacene -2,12-Diyl Diacetate

Pierre Vogel
1995
Journal Articles

Abstract

The addition of one equivalent of 2-nitrobenzenesulfenyl chloride to 1-(dimethoxymethyl)-2,3,5,6-tetramethylidene-7-oxabicyclo[2.2. 1]heptane (4) is highly regioselective giving 2-(chloromethyl)-1-(dimethoxymethyl)-5,6-dimethylidene-3 -[(-2-nitrophenylthio)methyl]-7-oxabicyclo[2.2.1]hept-2-ene (9). The reaction of 2-nitrobenzene-sulfenyl chloride with 8-(dimethoxymethyl)-9,10-dimethylidene-11-oxatricyclo[6.2.1.0(2,7)]undec -2(7)-en-4-yl methyl ketone derivatives (5, (-)-6) was also regioselective giving mixtures of 1,2- rather than 1,4-adducts resulting from competitive Markovnikov and anti-Markovnikov modes of addition, the olefinic moiety the furthest from the 8-dimethoxymethyl substituent being preferred. These adducts underwent base-induced eliminations with the formation of exocyclic thio- and chlorosubstituted dienes that added to 2,3-didehydroanisole to give products resulting from highly ''ortho'' regioselective Diels-Alder additions. The regioselectivity was the same whether 2,3-didehydroanisole was generated by nitrosation of 3-methoxy- or 6-methoxy-2-aminobenzoic acid. By applying these regioselective reactions to the Diels-Alder monoadduct of 3'-oxobut-2'-en-2'-yl (1R,5S,7S)-3-ethyl-2-oxo-3-aza-6,8-dioxabicyclo[3.2.1] octane-7-carboxylate (1-acetylvinyl RADO(Et)) with 1-(dimethoxymethyl)-2,3,5,6-tetramethylidene-7-oxabicylo[2.2.1]heptane (4), enantiopure (2R)-2-acetyl-1,2,3,4-tetrahydro-10-methoxynaphthacene-2,5-diyl diacetate and (2R)-5-(acetoxymethyl)-2-acetyl-1,2,3,4-tetrahydro-10-methoxynaphthacen- 2,12-diyl diacetate were prepared.

Official source

https://infoscience.epfl.ch/entities/publication/fb39a6eb-5cdb-463e-af78-98277786ba2a

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Pierre Vogel
1995
Journal Articles

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/fb39a6eb-5cdb-463e-af78-98277786ba2a

About this result

Related concepts (15)

1,3-Dipolar cycloaddition

The 1,3-dipolar cycloaddition is a chemical reaction between a 1,3-dipole and a dipolarophile to form a five-membered ring. The earliest 1,3-dipolar cycloadditions were described in the late 19th century to the early 20th century, following the discovery of 1,3-dipoles. Mechanistic investigation and synthetic application were established in the 1960s, primarily through the work of Rolf Huisgen. Hence, the reaction is sometimes referred to as the Huisgen cycloaddition (this term is often used to specifically describe the 1,3-dipolar cycloaddition between an organic azide and an alkyne to generate 1,2,3-triazole).

Regioselectivity

In chemistry, regioselectivity is the preference of chemical bonding or breaking in one direction over all other possible directions. It can often apply to which of many possible positions a reagent will affect, such as which proton a strong base will abstract from an organic molecule, or where on a substituted benzene ring a further substituent will be added. A specific example is a halohydrin formation reaction with 2-propenylbenzene: Because of the preference for the formation of one product over another, the reaction is selective.

Michael addition reaction

In organic chemistry, the Michael reaction or Michael 1,4 addition is a reaction between a Michael donor (an enolate or other nucleophile) and a Michael acceptor (usually an α,β-unsaturated carbonyl) to produce a Michael adduct by creating a carbon-carbon bond at the acceptor's β-carbon. It belongs to the larger class of conjugate additions and is widely used for the mild formation of carbon-carbon bonds.