P-Bromobenzoyl derivative

The relative stereochemistry of stephadiamine (16) was clarified by X-ray diffraction analysis, using the direct method, and the absolute configuration was solved by the heavy-atom method, using the N-p-bromobenzoyl derivative (6). Stephadiamine (16), a C-norhasubanan alkaloid, is not regarded as a hasubanan congener in the strict sense, but as a new member of oe-amino acid derivatives (6). 

The opening of the spiro (3-lactone of the anisatin-type sesquiterpene leads to the minwanensin-type. The structure of minwanensin (34) from the pericarps of I. minwanense was elucidated [9] and later revised by X-ray crystallographic analysis of its p-bromobenzoyl derivative [23], as shown in Fig. (6). This type of compounds, such as 3-acetoxy-14- -butyryloxy-10-deoxyfloridanolide (35), 14-acetoxy-3-oxofloridanolide (36), 13-acetoxy-14-(n-... 

The absolute configuration of caryose was determined applying the Exciton Chiral Coupling to 36 [Fig. (8)], which is the di-O-p-bromobenzoyl derivative, obtained as the main product of the isopropylidenation of the monosaccharide equilibrium mixture (34a, 34b and 35) followed by esterification with p-bromobenzoyl chloride. The results obtained have suggested for caryose the absolute configuration... 

The marine metabolite diazonamide A (47) (Fig. 3) was isolated from the colonial ascidian Diazona angulata, collected from the ceiUngs of caves along the northwest coast of Siquijor Island in the Phihppines [31]. The original structure of diazonamide A was suggested by an X-ray crystallographic study of the p-bromobenzoyl derivative of diazonamide B (48) (Fig. 3). Harran and coworkers completed the synthesis of the proposed diazonamide A [32], which differs from the natural diazonamide A, and thus the revised structure is 47 [33]. 

The principle of exciton coupling between vicinal benzoate chromophores has been extended to other aromatic carboxylic acid derivatives , including those of ring-substituted benzoic acids, 9-anthranoic acid (141) and p-methoxycinnamic acid (142). These derivatives have been widely used for the determination of the absolute stereochemistry in polyol natural products. The circular dichroism of the A -p-bromobenzoyl group combined with various 0-, 0,0 -di- and 0,0, 0"-tii-(p-bromobenzoyl) derivatives of 2-amino-2-deoxygalactopyranoside and an iV-anthranoyl group combined with tri-, tetra- and penta-p-methoxycinnamoyl derivatives of acyclic 1-amino polyols were studied to improve and develop microscale CD methods for the structural study of amino sugars. 

Zeorin (96), the most common lichen triterpene, has long been known. Its structure and stereochemistry were ultimately confirmed by X-ray analysis of 6a-bromobenzoyl zeorin. Leucotylin has structure (97) according to X-ray analysis of the 6-keto-16/3-p-bromobenzoyl derivative. While the side chain has also oconfiguration, the E ring exists in a half chair form in contrast to zeorin with an envelop conformation. 

The four related compounds oxalomycin (157), neooxalomycin (158), cur-romycin A (159), and curromycin B (160) were reported in 1985 157 and 158 were isolated from a yet to be identified Streptomyces species (79, 80) and 159 and 160 from an ethidium bromide-treated strain of S. hygroscopicus (81, 82). The absolute configuration of oxalomycin (157) and neooxalomycin (158) has been determined by application of a combination of X-ray crystallography and chemical correlation to degradation products, the important derivatives being the p-bromobenzoate 161, obtained from 157 by ozonolysis-reduction, acetylation, partial hydrolysis, and reacylation with p-bromobenzoyl chloride, and the erythro acetate 162 which was obtained along with the threo compound 163 after acetylation of the ozonolysis products of 157 (79, 80). No stereochemical infor-... 

The 1,5-Bis (o ), mp 209°, (m.-), mp 244° and (p-), top 262° derivs were prepd by Braun S Rudolph (Ref 2) by nitrating the parent compd with a l/l mist of fuming nitric acid + sulfuric acid on a water bath. Horwitz Gra-kauskas (Ref 4) prepd the l,5"Bis(p-dinitto) deriv by coupling diazotized p-nitroaniline with 1-acetyl-2-(4 -bromobenzoyl) hydrazine, separating the tetrazole following cyclization l (m-Nitrophenyl) 5-(p-nitfoph0nyl)-tetrazole, crysts, mp 170° (Ref 2)... 

Honda et al. [142] reported that l-phenyl-3-methyl-5-pyrazolone reacted with reducing carbohydrates aintost quantitatively to yield strongly UV-absorbing derivatives. This reaction differs from other derivatization reactions via the hydroxy group of carbohydrates, such as benzoylation or, p-bromobenzoylation, in that it gives no stereoisomers. This method is especially useful for the analysis of component monosaccharides of gly-... 

By the use of substituted benzoyl chlorides, derivatives such as the penta-O-(p-bromobenzoyl)- and penta-0-(p-nitrobenzoyl)-D-glucoses have been prepared. 

Nitrogen, Sulphur and Selenium-containing Compounds. - The S- and 6-substituted 3-amino-l,2,4-triazines 5 and 6, the spiro-naphthoxazine 7, the hetero Diels-Alder cycloadduct 8, 5-azido-3-0-benzyl-6-0-tert-butyldiphenylsilyl-5-deoxy-1,2-O-isopropylidene-P-L-talofuranose, 9 5-azido-6-0-benzoyl-3,5-dideoxy-3-fluoro-l,2-<9-isopropylidine-a-D-glucofuranose, kedarosamine (2,4-dideoxy-4-dimethylamino-L-fucopyranose) as the 3-0-(4-bromobenzoyl) derivative. 1,2 5,6-Di-0-isopropylidene-a-D-ribohexos-3-ulose phenylhydrazone, p-iactam 9 (from a diastereoselective [2+2] cycloaddition to a carbohydrate-based arylimine), 3 the D-arabino and D-ribo lactam derivatives 10 and 11, " the fully-protected iminosugar 12, 5 2,3,4,5-tetra-0-acetyl-6-amino-6-deoxy-D-mannonolactam, 4,8-anhydro-3-... 

Two polymorphs of a,a-trehalose octacetate monohydrate, 4,4 -dideoxy-a,a- ty/o-trehalose, methyl 2,3,4,6,2, 4, 6 -hepta-C -acetyl-a-laminaribinoside, 2 3,3 -dideoxy-a,a-flrflbjno-trehalosc. 3 Methyl 2,3-0-isopropylidene-5-0-tosyl-P-D-ribofuranoside 2, the 7-carbon glycoside 3 (see Chapter 17), C-glycosidic furanoside 4 (see Chapter 14) the oxazoline derivative 5 and methyl 1,6-di-0-(4-bromobenzoyl)-3,4-di-0-(4-methoxycinnamoyl)-P-D-fructofuranoside. Di-(3-deoxy-D-g/yccro-pcntulose)-l,2 2,r-dianhydridc, methyl 4,6-benzylidene-a-D-allopyranoside, methyl-2,3,4-tri-0-acctyl-a-L-rhamnopyranoside, l 2-(indol-3-yl)ethyl 2,3,4-tri-O-acetyl-a-L-... 

Acid Derivatives.— 2,2 5,6-Di-0-isopropylidene-2-C-hydroxymethyl-L-gulono-1,4-lactone/ AT-(2-chloroethyl)-D-gluconamide (n.d.)/ 5-azido-5-deoxy-AriV-diethyl-l,2-0-isopropylidene-3-(9-methanesulphonyl-P-L-iodoruranuron-amide/ 3,6-anhydro-7-(4-bromobenzoyl)-2-deoxy-4,5-0-isopropylidene-D-ahro-heptononitrile/ sodium o-isoascorbate, and reductic acid (2,3-di-hydroxycycIopent-2-enone). . 

Leucotylic acid (98), phlebic acid A (99), and phlebic acid B (100) are hopane derivatives with a 23-carboxylic acid from Parmelia leucotyliza yl., P. entotheiochroa Hue, and Peltigera aphthosa (L.) Willd. Diacetyl pyxinol (101), known from Pyxine endochrysina yX., possesses adammaran skeleton from X-ray analysis of 3/3, 12/3-di-/ -bromobenzoyl pyxinol. 

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