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Synthesis of Isoplagiochin A.-A convergent synthesis of title compound (IX), a plant metabolite isolated from plagiochila fruticosa, is presented. -(GERENCSER, J.; KESERUE, G. M.; MACSARI, I.; NOGRADI, M.; KAJTAR-PEREDY, M.; SZOELLOESY, A.; J.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

1997 organo-phosphorus compounds, nonmetal heterocycles organo-phosphorus compounds, nonmetal heterocycles S 0087 37 -200 1-(2,4,6-Tri-tert-butylphenyl)-3-methylphosphole: A Phosphole with a Significantly Flattened Phosphorus Pyramid Having Pronounced Characteristics of Aromaticity. -The title compound (V) is synthesized to test the effect of the strongly sterically demanding P-substituent on the geometry of the molecule. The phosphole ring, normally resistant to electrophilic substitutions, is found to react with AcCl/AlCl3 showing a considerable cyclic electron delocalization. -(KEGLEVICH, G.; BOECSKEI, Z.; KESERUE, G. M.; UJSZASZY, K.; QUIN, L. D.; J.

The macrocyclic diarylheptanoid garugamblin-2 (1) and its constitutional and sterical isomers 17-19 were synthesized using the isoxazole derivative 8 for the introduction of the 0-methoxyenone function. Ring closure was accomplished by an intramolecular Wittig reaction.Garugamblin-1 (2) and -2 (1) are members of the wider family of plant constituents called diarylheptanoids comprising both acyclic compounds such as curcumin ['] and macrocyclic ones, e.g. the acerogenins[21. Garugamblins-1 and -2 were isolated from the Indian shrub Guruga gumbleil3] and are closely related to the garuganins (e.g., garuganin 111), constituents of other Guruga specie~ [~-~]. A remarkable feature of all macrocyclic Gurugu constituents is the (a-P-methoxyenone function that imparts considerable strain to the ring system. Recently we have reported on the syntheses of garuganin IIIL7] and garugamblin-1 (2)r8l; in this paper we present that of garugamblin-2 (1).The strategy for the synthesis of the target compound was as follows: (i) Preparation of the diaryl ether part with functional groups suitable for the elaboration of the sevencarbon chain, (ii) addition of a five-carbon unit in which the precursor of the P-methoxyenone function of the target compound was masked, as suggested by Pollini et in the form of an isoxazole ring and (iii) ring closure by an intramolecular Wittig reaction.Our first task was to prepare the trivial, but hitherto unknown ester 3 which was done by methylenation of methyl gallate with CH212. Reaction of 3 with 4-fluorobenzaldehyde to give the diaryl ether 4 was remarkable in a way that it could be accomplished in refluxing DMF in the presence of K2C03 in acceptable yield without the addition of a copper compound, as required by the classical Ullmann ether synthesis. After protection of the aldehyde group by acetalization to 5, the ester group was converted in two steps (5 + 6 + 7) into an aldehyde function. The remaining five carbon atoms of the aliphatic chain were introduced in one step by reaction of 7 with the isoxazole derivative 8[']. The resulting EIZ mixture of olefins 9 was hydrogenated and the ester 10 reduced to the alcohol 11. Treatment of 11