Efficient syntheses of (±)-hydrangenol, (±)-phyllodulcin and (±)-macrophyllol
摘要:
In this paper we report on a efficient and flexible synthetic route towards the total syntheses of the dihydrocoumarine derivatives hydrangenol (1), phyllodulcin (1a) and macrophyllol (6b). The syntheses started with a readily available phosphonium salt 2 and suitable modified benzaldehydes 3/3a/3b resulting in 46 to 61% overall yields in three to four-steps sequences. The racemic products could be separated by chiral HPLC. The evidence of the(R)-enantiomer for sweetness could be demonstrated for la. (C) 2003 Elsevier Ltd. All rights reserved.
First totalsynthesis of AI-77-B (1), a gastroprotectivesubstance from Bacillus pumilus AI-77, was achieved in a stereoselective and convergent manner. In this synthesis, the dihydroisocoumarin part 2 was constructed in one step through 1,2-addition of the benzylic anion 17b to Boc-L-leucinal 7b. The hydroxy amino acid 4 was elaborated from (R)-glutamic acid in a highly stereoselective manner. Condensation
New Syntheses of Lunularic Acid and Some of Its Derivatives Efficient and convenient procedures are reported for the synthesis of lunularic acid (2) and for some of its derivatives on a preparative scale starting from the methyl ether 5 or the acetate 12 of ethyl 6-methylsalicylate (4) and introducing the bibenzyl moiety by metalation/ alkylation or by bromination / Wittig reaction/ hydrogenation sequences.
Salicylic acid derivatives of the formula I ##STR1## (R.sup.1 is succinimidoxy; unsubstituted or substituted hetaryl; OR.sup.5 where R.sup.5 is substituted or unsubstituted cycloalkyl, alkyl, alkenyl, alkynyl, phenyl or substituted methyleneamino; OR.sup.8 where R.sup.8 is hydrogen, alkali metal or alkaline earth metal cation, ammonium or organic ammonium; R.sup.2 and R.sup.3 are each C.sub.1 -C.sub.4 -alkyl, C.sub.1 -C.sub.2 -haloalkyl, C.sub.1 -C.sub.4 -alkoxy or C.sub.1 -C.sub.2 -haloalkoxy and/or C.sub.1 -C.sub.4 -alkylthio; R.sup.4 is ethynyl or unsubstituted or substituted vinyl; X is oxygen or sulfur; Z is nitrogen or methine) are used as herbicides and bioregulators.
Salicylsäurederivate der Formel I
(R1 Succinimidoxy; unsubstituiertes oder substituiertes Hetaryl; OR5, in der R5 substituiertes oder unsubstituiertes Cycloalkyl, Alkyl, Alkenyl, Alkinyl, Phenyl oder eine Oximgruppe bedeutet; OR8, in der R8 Wasserstoff, Alkalimetall-, Erdalkalimetallkation, Ammonium oder organisches Ammonium bedeutet;
R2, R3 C1-C4-Alkyl, C1-C2-Halogenalkyl, C1-C4-Alkoxy, C1-C2-Halogenalkoxy und/oder C1-C4-Alkylthio;
R4 Ethinyl, unsubstituiertes oder substituiertes Vinyl;
X Sauerstoff, Schwefel;
Z Stickstoff, Methingruppe)
Die Verbindungen I dienen als Herbizide und Bioregulatoren.
式 I 的水杨酸衍生物
(R1为琥珀酰亚胺氧基;未取代或取代的庚二基;OR5,其中R5为取代或未取代的环烷基、烷基、烯基、炔基、苯基或肟基;OR8,其中R8为氢、碱金属阳离子、碱土金属阳离子、铵或有机铵;
R2、R3 为 C1-C4 烷基、C1-C2 卤代烷基、C1-C4 烷氧基、C1-C2 卤代烷氧基和/或 C1-C4 烷硫基;
R4 乙炔基、未取代或取代的乙烯基;
X 氧、硫;
Z 氮、甲基)。
化合物 I 可用作除草剂和生物调节剂。
Enantiodifferentiation in Taste Perception of the phyllodulcins
作者:Reinhard Zehnter、Hans Gerlach
DOI:10.1016/0957-4166(95)00367-x
日期:1995.11
Both enantiomers of phyllodulcin 1 have been prepared. Ester 2 was synthesized in a Wittig reaction from O-benzyl isovanillin. The corresponding stilbene carboxylic acid 3 could be cyclized with CF3CO2H to produce the 3'-benzyl ether 4 of (+/-)-phyllodulcin. Acylation with (1R,4S)-camphanoyl chloride gave first 5 and after hydrogenolysis of the benzyl ether group in 5 the diastereomeric esters 6. The diastereomerically pure 8-(1R,4S)-camphanoate (+)-6 of (R)-phyllodulcin could be isolated by repeated recrystallization. With (1S,4R)-camphanoyl chloride the enantiomeric 8-(1S,4R)-camphanoate (-)-6 of O-phyllodulcin could be prepared via ent-5 from a mixture of the diastereomeric esters ent-6. Ethanolysis of (+)-6 gave (R)-phyllodulcin [(+)-1] with 99% ee. The enantiomeric (S)-(-)-1 with 98% ee could be obtained from (-)-6. While (+)-1, the enantiomer occuring in fermented leaves of amacha, has an intense sweet taste, the enantiomer (-)-1 is completely tasteless.