Gold Catalysis: Efficient Synthesis and Structural Assignment of Jungianol and epi‐Jungianol

Abstract

Starting from 2-methylfuran and crotonaldehyde, both jungianol and epi-jungianol were prepared by a six-step sequence including a gold-catalyzed arene synthesis and a photochemical S(N)2-like reduction with lithium aluminum hydride. Not a single protective group was needed in the entire synthesis. With both diastereomers in hand, the stereochemical assignment in the literature could be corrected by means of a thorough (1)H NMR spectroscopic analysis and an X-ray diffraction study on an epi-jungianol derivative.

Asymmetric Rhodium‐Catalyzed Hydrogenation Meets Gold‐Catalyzed Cyclization: Enantioselective Synthesis of 8‐Hydroxytetrahydroisoquinolines

“…[6] The new gold-catalyzed phenol synthesis is probably the best tool to obtain such 8-hydroxytetrahydroisoquinolines (Scheme 2). [7][8][9] Starting from furfurals 12 with different substituents, (Z)-dehydroamino acid esters 11 can be prepared and subseAbstract: Different furyl-substituted (Z)-dehydroamino acid derivatives were hydrogenated with the rhodium/ MandyphosA C H T U N G T R E N N U N G (OMe)-system to give enantiomeric excesses between 80 and 98 %. The absolute configuration of the newly formed stereogenic center was determined by anomalous diffraction to be R. These chiral furyl alanines were transferred into 8-hydroxytetrahydroisoquinolines by employing goldcatalyzed arene synthesis as the key step.…”

Síntese de indanos: uma seleção de métodos gerais e eficientes

“…Esta cetona foi transformada em duas etapas em uma mistura do sesquiterpeno natural jungianol e de seu epímero cis, sendo este último em maior proporção 23 (Esquema 17).…”

Gold Catalysis: Phenol Synthesis in the Presence of Functional Groups

“…[9] The only example in natural product synthesis so far is the total synthesis of the sesquiterpene Jungianol in six steps without using a single protecting group. [10] In most of the known examples apart from an N-sulfonyl group, an oxygen atom, or a propargylic carbonyl group in the tether no functional groups other than the reacting alkyne and furan subunits were present (Table 1, entries [1][2][3][4][5][6][7][8][9]. The only exception is with substrate 1 j ( Table 1, entry 10), for which the initially formed o-alkynylphenol isomerizes to the benzofuran 6 in a second gold-catalyzed step.…”