A-methylanthranilate

The main components are limonene (65-75%) and q-terpinene (16-22%). The characteristic feature of mandarin oil is its content of a-sinensal (0.2-0.5%), methyl A-methylanthranilate (0.3-0.6%, which is responsible for fluorescence), and long-chain unsaturated aliphatic aldehydes [369, 370a, 370d, 370e, 381, 394c, 414-421b]. 

Petitgrain oils are obtained by steam distillation of the leaves of citrus trees. The oils derived from the bitter orange tree are the most important. Other petitgrain oils (mandarinier, citronnier, and bergamottier) are less important. Petitgrain oil mandarinier is a source of natural methyl A -methylanthranilate, which is present at a concentration of nearly 50%. Petitgrain oils are essential constituents of eau de cologne. 

Scheme 23.22 Some nitrogen-containing flavour compounds produced by microorganisms, a Methylanthranilate formation from N-methyl methylanthranilate 1 Trametes sp., Polyporus sp. b Different pyrazines produced with microorganisms in optimised media 2 mutant strain from Pseudomonas perolens ATCC 10757 3 Bacillus subtilis, Brevibacterium linens 4 mutant strain of Corynebacterium glutamicum...

Y-glutamyl-/i-phenylene-diamine-3-carbonicacid A -methylanthranilic acid Potassium hexacyanoferate (III)... 

Derivation Methylation of methyl anthranilate or esterification of A-methylanthranilic acid. 

Two molecules of A -methylanthranilic acid react together when heated with thionyl chloride to give a high yield of the diazocinedione. 

Methylthio-l,2,4-triazin-5(2//)-ones (209) have been converted into 3//-[l,2,4]triazino[3,2-i]quinoxaline-3,10(4//)-diones (212) upon cyclocondensation with anthranilic acid (210) (Scheme 40). A-Methylanthranilic acid (211) with (209) afforded the 5-methyl-3/f-[l,2,4]triazino[3,2- )]quin-azoline-3,10(5//)-diones (213) (Scheme 40). Reaction of 2-methyl-3-methylthio-6-phenyl-l,2,4-tri-azin-5(2//)-one (214) with anthranilic acid (210) gave 1-methyl-3-phenyl-47/-[l,2,4]triazino[3,4-i]quinazoline-4,6(l//)-dione (216) via the intermediate (215) (Scheme 41) <84CB1077, 84CB1083). 3-Alkylthio-4-amino-l,2,4-triazin-5(4//)-ones (217) with anthranilic acid formed l-amino-3/f-... 

A/-methylanthranilic acid (A/-MANT) Figure 4.29 Newer generation of fluorescent probes and tags. 

A one-step synthesis of acridones takes advantage of somewhat similar chemistry . Treatment of methyl A-methylanthranilate 570 with lithium A-isopropylcyclohexylamide (LilCA) in THE generated A-lithio salt 571 addition of a halobenzene as the aryne source then produced the acridone 572 as shown, in good yield (40-60%). Substituted haloarenes gave substituted acridones. Utility of the method was demonstrated with a short synthesis of the alkaloid acronyeine 573. 

Small amounts of A-methylanthranilate occur in a number of essential oils (Groger, 1980). Another simple representative, damascenine (2), is found in the seeds of Nigella damascena L. (Ranunculaceae) (Fig. 31.2). This alkaloid has been shown to come from shikimic acid via anthranilic acid (Cordell, 1981). [ CHsl-Methionine is an efficient precursor of all three bound methyl groups (Groger, 1980 Geiss-man and Crout, 1969). 

The reaction of soybean peroxidase on methyl A -methylanthranilate produces methylanthranilate [905]. This conversion was followed by separation on a Cg column (2 = 332nm) using a 50-min 100/0/0.1 - 50/50/0.1 water/acetonitrile/ TEA. gradient. Elution was. complete in <30 min, peaks were well resolved, and peak shape was excellent. No interferents were observed, and so a shorter, steeper gradient seems advisable. 

A sn and /csn couplings measured by Renamy et al for triorganotin(IV) derivatives of 3,5-dinitrobenzoate, A-methylanthranilate and dicyclohexylace-tate ligands were consistent with a tetrahedral environment around the tin centre. 

Faulhaber et al. [30,31] analyzed mandarin essential oils by measuring 8 C ratios of characteristic flavor compounds of this product. Mandarin oils, which are obtained by cold-pressing the peel of the fruits of Citrus reticulata Blanco, are used in the food industry and in perfume compositions. The main constituents of mandarin essential oil are limonene (approximately 69%) and y-terpinene (ap proximately 20%), even though the fragrance of this oil is mostly determined by minor components such as methyl A-methylanthranilate (approximately 0.4%) and a-sinensal (approximately 0.3%). Evaluation of genuineness of this product is of special interest, since synthetic analogs of the essential oil components are commercially available. In this context, measurements of 8 C and 8 N of methyl -methylanthranilate [30] and of 5 C of characteristic flavor components in this oil proved helpful in the authenticity assessment of cold-pressed mandarin oil [31]. The characteristic profile of mandarin essential oil so established could be applied to the authenticity control of commercially available mandarin oils. 

Tandem metallation synthesis of acridones was also successfully applied by Watanabe to the synthesis of acronycine (2) (314). Thus, the lithium sdt of methyl A -methylanthranilate (250) easily reacted with the benzyne 348 generated from 6-bromo-9-methoxy-2,2-dimethylchromene (349) (357) to afford directly acronycine (2) in 41% yield. 

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