Isophakellin alkaloids

Applications of l,n-ADEQUATE in the elucidation of the structures of phakellin and isophakellin alkaloids... 

The most recent report of Myer and Kock47 afforded a more robust assessment of the value of 1,1-ADEQUATE data as a part of the input data set for the COCON CASE program. The output of the structure generation for the brominated phakellins (18a, b) and brominated isophakellin (19a, b) alkaloids is summarized in Table 3. Structures generated without specified hybridization are noted on the first line for each compound that can be compared with the number of structures generated when pre-defined hybridization was employed on the second line for each... 

Figure 7. Polyciclic N7/C11 + C4/C12 derivatives the isophakellins (49 - 54) and Styloguanidines (55-57) family alkaloids.

Molecules isomeric with those of the previous group are N7/C11 + C4/C12 derivatives, differing in the linkage of the imidazole carbon C-12 with C-4 in place of N-1. They constitute the isophakellins family alkaloids (49-54, Figure 7) [49-53],... 

The reader interested in the appHcation of 1,1 - and 1, -ADEQUATE in the elucidation of the structures of the phakellin and isophakellin alkaloids can find a discussion of that aspect of the structure elucidation either in the Meyer and Kdck [91] manuscript or the topic is also extensively discussed in the 2011 review of the use of 1,1- and 1, -ADEQUATE data in structure elucidation by Martin [92], 1,1-ADEQUATE data, in particular, can be quite useful in estabhshing the adjacency of pairs of protonated carbons or protonated carbons and adjacent quaternary carbons. 1, n-ADEQUATE data are complimentary to EIMBC data in that the most prevalent correlation observed in a 1, -ADEQUATE spectrum is via Jcc> which is equivalent to a cH correlation in an HMBC spectrum. The interested reader should also be aware of an experiment known as dual-optimized inverted Jcc 1adequate that affords both Jcc and "Jcc correlations in a single experiment, the former correlations are inverted while the latter group has positive phase [93]. 

We described this important family of heterocydic derivatives in the section on sponges of the order Agelasida. Alkaloids of phakellin and isophakellin, isolated during the 1970s from sponges of the genus Phakellia, are probably the earliest examples of such heterocydes. Some... 

---