New Structures and Stereochemistry

New Structures and Stereochemistry.—Carotenoids. Of the few new carotenoid structures that have been reported, all but one are from marine animals. Lac-tucaxanthin, a major xanthophyll in chloroplasts of lettuce (Lactuca sativa) and 

Siefermann-Harms, S. Hertzberg, G. Borch, and S. Liaaen-Jensen, Phytochemistry, 1981, 20, 85. 

Litchfield and S. Liaaen-Jensen, Comp. Biochem. Physiol., 1980, 66B, 359. 

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New Structures and Stereochemistry.—New Carotenoid Structures. A mutant strain of Rhizobium lupini contains a new nor-carotenoid, 2, 3 -trans-dihydroxy-2-nor-/3,/3-carotene-3,4-dione (1)." The wild-type R. lupini, when cultured in the presence of the cyclization inhibitors nicotine or CPTA, produced three new monocyclic carotenoids, 2,3-h-ans-dihydroxy-/3,-caroten-4-one (2), 3-hydroxy-/3,(/ -caroten-4-one (3), and p,tf/-carotene-2,3-trans-dio (4)," which were characterized by m.s. and n.m.r. The light absorption and mass spectra of a carotenoid from Rhodopseudomonas capsulata allowed its identification" as demethylspheroidenone [l-hydroxy-3,4-didehydro-l,2,7, 8 -tetrahydro- /f,(/f-caroten-2-one (5)]. 

New Structures and Stereochemistry Bicyclic Carotenoids Monocyclic Carotenoids Acyclic Carotenoids Apocarotenoids Degraded Carotenoids Synthesis and Reactions Carotenoids Retinoids... 

New Structures and Stereochemistry.—Carotenoids. A major pigment in aerobic cultures of Rhodopseudomonas capsulata has been identified by spectroscopic... 

An extremely interesting and novel method has been described (91TL133). The principle involved is the intramolecular Diels-Alder addition of a 2,4-dienoic acid amide with an azodicarbonyl moiety. /V-Sorbyl-proline (27) was condensed with an acylhydrazine to form (28). Oxidation of this with lead tetraacetate (LTA) in boiling benzene resulted in the piperazinedione (30). This must have come about via (29), which could undergo an intramolecular Diels-Alder reaction. The structure and stereochemistry of (30) were confirmed by X-ray crystallography. The two new chiral centers have the R configuration as shown in (Scheme 9). 

Ciminiello P, Dell Aversano C, Fattorusso E, Forino M, Magno S, Di Rosa M, Ianaro A, Poletti R (2002) Structure and Stereochemistry of a New Cytotoxic Polychlorinated Sulfolipid from Adriatic Shellfish. J Am Chem Soc 124 13114... 

The structure and stereochemistry of chuangxinmycin (11a), a new antibiotic isolated from the micro-organism Actinoplanes tsinanensis, collected from a soil sample in Shantung Province, China, have been confirmed by synthesis (Scheme l).12a Chuangxinmycin contains a novel heterocyclic ring system, and is claimed to be effective in the treatment of septicaemia and urinary and biliary infections. 

Bhat SV, Bajqwa BS et al (1977) Structures and stereochemistry of new labdane diterpinoids from coleus forskohlii briq. Tetrahedron Lett 18 1669-1672... 

The new groups formed in these reactions are (rans-related, and the proportion of each isomer formed depends on the structure and stereochemistry of the parent sugar epoxide. When attached to rigid, six-membered... 

Over 40 alkaloids have been isolated from Lythraceous plants since Ferris isolated 7 alkaloids from Decodon verticillatus in 1962 (/). Before the last review in this treatise (2), the structures and stereochemistries of all Lythraceous alkaloids had been established. No reports on the isolation of new alkaloids from this family have been published since 1981. On the other hand, development of new synthetic technologies has opened new avenues to the total synthesis of Lythraceous alkaloids. The earlier classification (types A-E) of Lythraceous alkaloids introduced by Fuji et al. (J) and adopted in the last review (2) is not used in this chapter because it does not indicate the structural features. This chapter covers the literature from 1979 to 1987, except for two papers (4, 5) already included in the last review (2) in Volume 18 of this treatise. 

Bulbs of F. camtschatcensis yielded solanidine (36a) together with traces of hapepunine (34a), veralkamine, an unidentified dihydroxy-spirosolane, and a new aglycon, i.e. camtschatcanidine (36b).54 The structure assigned to camtschat-canidine was deduced from the spectroscopic data, and in particular by comparison of its 13C n.m.r. spectrum with that of solanidine. The structure and stereochemistry proposed were proven by the reduction (by LiAlH4) of the O-acetyl-O-tosyl derivative (36c) of camtschatcanidine to yield solanidine. 

Kaneko has reported the isolation of isobaimonidine (38c), which is a new epimer of verticine (38a), from aerial parts of F. thunbergii.56 The structure and stereochemistry of isobaimonidine were established by its synthesis from verticine. 

Pakrashi s group (512) has isolated two new alkaloids from the seeds of A. lamarckii and, on the basis of spectral and chemical evidence, inferred them to be 9-demethylprotoemetinol (153) and 10-demethylprotoemetinol (154). Fujii et al. (513) have confirmed the structure and stereochemistry of the second alkaloid by synthesizing ( )-154, (—)-154, and their diacetates from the ( )-ethyl ester (94) and the (—)-ethyl ester (100) of the tricyclic... 

Since Hirata et al. began research into daphniphyllum alkaloids in 1966, a number of new alkaloids have been discovered. As a result, the number of known daphniphyllum alkaloids has grown markedly in recent years to a present count of 118 (compounds 1-118). These alkaloids, isolated chiefly by Yamamura and Hirata et al. are classified into six different types of backbone skeletons [1-3]. These unusual ring systems have attracted great interest as challenging targets for total synthesis or biosynthetic studies. This chapter covers the reports on daphniphyllum alkaloids that have been published between 1966 and 2006. Since the structures and stereochemistry of these alkaloids are quite complex and the representation of the structure formula has not been unified, all the natural daphniphyllum alkaloids (1-118) are listed. Classification of the alkaloids basically follows that of the previous reviews [1,2], but sections on the newly found skeletons have been added. 

Structure-activity correlations have been examined for several A-nor-thia-steroids of type (220). Several new studies have been devoted to the synthesis of A-nor-steroids. Pinacol-type rearrangement of 3a-hydroxy-2a-mesyloxy-3/S-methylcholestane (221) led to 2)8-acetyl-A-norcholestane (222). Its structure and stereochemistry were confirmed by Baeyer-Villiger oxidation, which afforded the known 2 -acetoxy-A-norcholestane (223) ... 

Spiropiperidine Alkaloids.—new synthetic pathway to ( )-perhydro-histrionicotoxin (27) (Scheme 5) has been elaborated. The final product is the intermediate (28), convertible to (27) as described earlier. A further synthetic entry into this ring system uses a Mannich-type spiro cyclization as key step and leads ultimately to racemic 2,7-epiperhydrohistrionicotoxin (29) (Scheme 6). The structure and stereochemistry of the urethane intermediate (30) were ascertained by X-ray diffraction analysis. ... 

The known alkaloid cocculine (1 R = H) has been isolated from two new sources, Cocculus carolinus and C. trilobus C. carolinus also yielded cocculolidine (2) while C. trilobus was shown to elaborate the new base coccutrine (1 R = OMe). The structure and stereochemistry of cocculine and of coccutrine were established by X-ray crystallographic analysis/ Russian workers have advanced the absolute configuration for cocculine enantiomeric with that described by structure (1) on the... 

With the aid of decoupling experiments and the INDOR technique, it was possible to define completely the structure and stereochemistry of erythristemine (1) with the exception of the configuration at C-11." In order to obtain the latter information, recourse was taken to A-ray analysis on the 2-bromo-4,6-dinitrophenolate salt of (1). This constitutes a new method and may be applicable elsewhere. Details of the structural and stereochemical elucidation of the interesting insecticidal alkaloid (2), which may be regarded as a ring-D degraded erythroidine structure, have appeared. ... 

The structure and stereochemistry of chiloscyphone (74) have been determined and o.r.d. and c.d. spectra are consistent with a non-steroidal conformation. " From Taiwania cryptomerioides, three new muurolane-type sesquiterpenoids have been isolated" viz., (75), (76), and (77). In accordance with the absolute... 

A new synthesis of ( )-crinan (43), a compound possessing the basic ring skeleton of the alkaloid crinine, using a stereoselective photocyclization reaction has been devised.28 The imine (39), readily prepared from 2-allylcyclohexanone and benzylamine, was acetylated with piperonyloyl chloride to give the AT-acylena-mine (40). Photolysis of (40) in methanol solution gave compound (41) (15% yield) whose structure and stereochemistry were established by spectral means and by consideration of the proposed electrocyclic nature of the reaction. 

A recent communication by Kumar and co-workers reported the isolation of a new binary tetrahydrocarbazole-indole alkaloid, methyl 2-methyl-4-(iV-2")8-methyl-l",2",3",4"-tetrahydrocarbazol-l"a-ylindol-3 -yl butanoate (77), C27H30N2O2 from the root timber of Murraya gleniei (67). It exhibited spectral data characteristic of an indole with an ester function. The mass spectral fragments having m/z 231 and 184 indicated that it was a binary alkaloid consisting of C14H17N02 and Q3H14N units. The structure and stereochemistry of 77 were established by the application of 1H, 13C, DEPT,... 

Elaeocarpine, CieHigOaN (mp 81° [ajj, +0.1°) and isoelaeocarpine (mp 51° [a]u +0.4°) are two new indolizidine alkaloids of a new structural type. The complete structure and stereochemistry of elaeocarpine were determined by X-ray crystal structure analysis of its hydrobromide as LX. Its isomer, LXI, is obtained from LX by treatment with metha-nolic potassium hydroxide at room temperature. Spectral data are in accord with these structures (86). 

Nemorosonol was obtained from the benzene extract of ground fresh fruits of C. nemorosa. Spectral data indicated that (107) is a PBD incorporating four five-carbons units. Structural details were determined on the basis of NMR data. NMR spectral parameters were recorded in CgDg solutions because of the predominance of one tautomer was observed. Nemorosonol represents the unique PBD with a tricyclo-[4.3.1.03,7]-decane skeleton isolated so far [39]. The structure and stereochemistry at C-5 were revised in a new study employing an X-ray crystallographic method. This study also permitted to identify the presence of two cristallographically independent molecules for nemorosonol in the unit cell [55]. 

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