The reports of bicyclic 6-6 systems with one bridgehead nitrogen atom and four extra heteroatoms are sparse in the literature. Since the last review,1 only twelve new bicyclic 6-6 derivatives 23–34 have been reported.2, 3, 4, 5, 6, 7, 8, 9, 10, 11 In all cases, synthesis of the new structures started from substituted 4-amino-3-thioxo-1,2,4-triazin-5-ones. In most cases, NMR spectroscopy, mass spectrometry and IR spectroscopy were used to characterize the compounds. Compounds 23, 26 and 27 show good biological activity.

Chemoenzymatic synthesis and modification of well-defined macrolactonic sophorolipid (SLML) analogues via a series of successive regioselective de-esterification/transesterification reactions is investigated. Of the lipases screened, Candida antartica lipase- B (Novozyme-435) successfully deacylated the C-6′ acetoxy group of natural and peracylated SLMLs. Subsequent transesterification with acylating agents (esters of fatty acids) was successful only with the C-6′ deacetylated natural SLML providing an avenue to well-defined analogues of varying amphilicity. The macrolactonic motif was essential for enzymatic recognition of the sophorose rings of these complex glycolipids. In the absence of the lactonic motif, the peracylated sophorose rings are not deacylated, rather the carboxyl end of the non-lactonic forms that was preferentially transesterified. All macrolactonic derivatives were characterized by IR, 1H, 13C, 1H-1H and 1H-13C NMR spectroscopy, as well as HRMS where applicable.

Methods for the preparation of deuterium-labeled analogs to six prominent biotransformation products of the explosive 2,4,6-trinitrotoluene were developed. These are useful as reference standards for stable isotope dilution techniques and for solid state 2H NMR spectroscopic studies. Although syntheses for most of the target compounds in protiated form had been reported in the past, most of those were found to be poorly suited for the preparation of the deuterated materials. Selective reduction of [2H5]trinitrotoluene furnished [2H5]-4,6-dinitro-2-hydroxylaminotoluene, [2H5]-2,6-dinitro-4-hydroxylaminotoluene, [2H5]-2-amino-4,6-dinitrotoluene, and [2H5]-4-amino-2,6-dinitrotoluene. The syntheses of [2H10]-2,2-azo-4,4,6,6-tetranitrotoluene and [2H10]-4,4-azo-2,2,6,6-tetranitrotoluene were accomplished by selective oxidation of [2H5]-2-amino-4,6-dinitrotoluene and [2H5]-4-amino-2,6-dinitrotoluene, respectively.

Various lanthanide open framework materials incorporating the terephthalate (TP) entity were prepared using hydrothermal synthesis methods at a moderate temperature of 170°C. The compounds Nd2(TP)3(H2O)4(1), Er2(TP)3(H2O)4(2), Yb2(TP)3(H2O)2(3), Yb2(TP)3(H2O)6(4), and Yb2(TP)3(H2O)8·2H2O (5), were characterized by single crystal structural analysis and FT-IR spectroscopy. While compounds 1 and 2 have been reported before on the basis of powder X-ray diffraction, the structural characterization of any ytterbium terephthalate species is unprecedented. Compounds 1–5 crystallize in triclinic settings with space group P-1. The compounds are compared with their previously reported Er and Tb-counterparts and the reduction of the dimensionality of the resulting networks from 3D over 2D to 1D with increasing level of hydration is discussed. Compounds 1, 2, and 3 with the lowest water content assemble in three-dimensional network lattices. Compounds 4 and 5, however, form 2D layered systems and 1D rod like chains, respectively, which are held together by hydrogen bonds originating from coordinating H2O. The crystal lattices of the 3D networks experience higher levels of tension as can be seen by increasing out-of-plane torsion with regard to the terephthalate carboxylate groups. Moreover, there seems to be a correlation between the level of strain on the aromatic ligands and the reduction of the number of carboxylate oxygen atoms that are part of the coordination polyhedra.

ChemInformVolume 34, Issue 52 Natural Products Enzyme-Catalyzed Regioselective Transesterification of Peracylated Sophorolipids. Jason A. Carr, Jason A. Carr Dep. Chem., Univ. South Fla., Tampa, FL 33620, USASearch for more papers by this authorKirpal S. Bisht, Kirpal S. Bisht Dep. Chem., Univ. South Fla., Tampa, FL 33620, USASearch for more papers by this author Jason A. Carr, Jason A. Carr Dep. Chem., Univ. South Fla., Tampa, FL 33620, USASearch for more papers by this authorKirpal S. Bisht, Kirpal S. Bisht Dep. Chem., Univ. South Fla., Tampa, FL 33620, USASearch for more papers by this author First published: 04 December 2003 https://doi.org/10.1002/chin.200352216AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume34, Issue52December 30, 2003 RelatedInformation