Malevamide D:  Isolation and Structure Determination of an Isodolastatin H Analogue from the Marine Cyanobacterium <i>Symploca hydnoides</i>.

Horgen, F. David; Kazmierski, Emily B.; Westenburg, Hans E.; Yoshida, Wesley Y.; Scheuer, Paul J.

doi:10.1021/np020473e

Cited by 5 publications

(11 citation statements)

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“…To determine which of the possible vertices that V 1 is bound to, we must consider other correlations associated with each of the possibilities. In doing so, we begin with an analysis of the bonds emanating from the ν 7 (CH 3 ) vertex with connectivities C 12 (7)(8)(9)(10), C 12 (7)(8)(9)(10)(11), C 12 (7)(8)(9)(10)(11)(12)(13)(14), and C 12 (7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23) which shows that the ν 7 vertex can be connected with only one of the vertices ν 10 , ν 11 , ν 14 , and ν 23 ; in addition, this vertex must be tetravalent. Among the mentioned vertices, only the ν 11 vertex possesses this property indicating the ν 7 vertex must be connected with the ν 11 vertex.…”

Section: Nonstandard Connectivity Removal When Vertices and Groups Of...mentioning

confidence: 99%

“…Thus, the following fragment is established: Continuing, the bonds of the ν 16 (CH) vertex are analyzed. This vertex has the following 7 connectivities: C 11 , C 12 , C 12 , C 12 (16)(17), C 12 (16)(17)(18)(19)(20)(21), C 12 (16)(17)(18)(19)(20)(21)(22), and C 12 (16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26).…”

Section: Nonstandard Connectivity Removal When Vertices and Groups Of...mentioning

confidence: 99%

“…D 2 C (V 16 ) ) 1. At the same time, from the connectivities C 12 (16)(17)(18)(19)(20)(21)(22) and C 12 (16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26) it follows that two vertices, ν 22 and ν 26 , must also be present in the second layer of the n 16 vertex environment, i.e., K 2 (V 16 ) ) 2. As a result K 2 (V 2 ) > D 2 C (V 2 ) and consequently the unique bond distribution of the ν 16 vertices is inadmissible.…”

Section: Nonstandard Connectivity Removal When Vertices and Groups Of...mentioning

confidence: 99%

“…In case of the analysis of horiolide (3), 20 whose 2D NMR spectra contain five nonstandard connectivities C 22 (17)(18)(19)(20)(21)(22)(23), C 22 (7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23), C 22 (7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17), C 22 , C 33 (6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17) in the COSY data and 1 nonstandard C 33 connectivity in the HMBC spectrum (remember that they are accepted by the program as having lengths common for COSY and HMBC) as indicated with arrows on the structure, the program found and automatically removed all contradictions. As a ...…”

Section: H Nmr Spectrum (See the Examples Below)mentioning

confidence: 99%

“…In so doing, the HMBC data are analyzed again, as these data may contain no contradictions or the contradictions may be resolvable and, consequently, a solution can be found. In the previous example if the COSY data of triterpene E are excluded from consideration, only one nonstandard HMBC connectivity C 33 (12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26) is left. The new MCD was checked, but the program did not detect the one remaining contradiction.…”

Section: Resolving Contradictions In Complicatedmentioning

confidence: 99%

See 4 more Smart Citations

Structure Elucidation from 2D NMR Spectra Using the StrucEluc Expert System: Detection and Removal of Contradictions in the Data

Molodtsov

Elyashberg

Blinov

et al. 2004

J. Chem. Inf. Comput. Sci.

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The elucidation of chemical structures from 2D NMR data commonly utilizes a combination of COSY, HMQC/HSQC, and HMBC data. Generally COSY connectivities are assumed to mostly describe the separation of protons that are separated by 1 skeletal bond (3JHH), while HMBC connectivities represent protons separated from carbon atoms by 1 to 2 skeletal bonds (2JCH and 3JCH). Obviously COSY and HMBC connectivities of lengths greater than those described have been detected. Though experimental techniques have recently been described to aid in the identification of the nature of the couplings the detection of whether a coupling is 2-bond or greater still remains a challenge in most laboratories. In the StrucEluc software system the common lengths of the connectivities, 1-bond for COSY and 1- or 2-bond for HMBC, derived from 2D NMR data are set as the default. Therefore, in the presence of any extended connectivities contradictions can appear in the 2D NMR data. In this article, algorithmic methods for the detection and removal of contradictions in 2D NMR data that have been developed in support of StrucEluc are described. The methods are based on the analysis of molecular connectivity diagrams, MCDs. These methods have been implemented in the StrucEluc system and tested by solving 50 structural problems with 2D NMR spectral data containing contradictions. The presence of contradictions was detected by the algorithm in 90% of the cases, and the contradictions were automatically removed in approximately 50% of the problems. A method of "fuzzy" structure generation in the presence of contradictions has been suggested and successfully tested in this work. This work will demonstrate examples of the application of developed methods to a number of structural problems.

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