Doubly or bisconjugated steroid metabolites have long been known as minor components of the steroid profile that have traditionally been studied by laborious and indirect fractionation, hydrolysis and gas chromatography-mass spectrometry (GC-MS) analysis.Recently, the synthesis and characterisation of steroid bis(sulfate) (aka disulfate or bissulfate) reference materials enabled the liquid chromatography-tandem mass spectrometry (LC-MS/MS) study of this metabolite class and the development of a constant ion loss (CIL) scan method for the direct and untargeted detection of steroid bis(sulfate) metabolites. Methods for direct LC-MS/MS detection of other bisconjugated steroids, such as steroid bisglucuronide and mixed steroid sulfate glucuronide metabolites, have great potential to reveal a more complete picture of the steroid profile. However, access to steroid bisglucuronide or sulfate glucuronide reference materials necessary for LC-MS/MS method development, metabolite identification or quantification is severely limited. In this work, ten steroid bisglucuronide and ten steroid sulfate glucuronide reference materials were synthesised through an ordered combination of chemical sulfation and/or enzymatic glucuronylation reactions. All compounds were purified and characterised using NMR and MS methods. Chemistry for the preparation of stable isotope labelled steroid { 13 C 6 }glucuronide internal standards has also been developed and applied to the preparation of two selectively mono-labelled steroid bisglucuronide reference materials used to characterise more completely MS fragmentation pathways. The electrospray ionisation and fragmentation of the bisconjugated steroid reference materials has been studied.Preliminary targeted ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) analysis of the reference materials prepared revealed the presence of three steroid sulfate glucuronides as endogenous human urinary metabolites.Highlights  Ten steroid bisglucuronide reference materials synthesised and characterised  Ten steroid sulfate glucuronide reference materials synthesised and characterised  Stable isotope labelled internal standards using 18 O and 13 C prepared  Electrospray ionisation and fragmentation of reference materials studied  Three steroid sulfate glucuronide metabolites confirmed in human urine Keywords:Steroid bisglucuronide; steroid sulfate glucuronide; steroid conjugate; phase II metabolism; stable isotope labelled internal standard; mass spectrometry. AbbreviationsCID = collision induced dissociation, CIL = constant ion loss, DHEA = dehydroepiandrosterone, EA = epiandrosterone, E. coli = Escherichia coli, GC-MS = gas chromatography-mass spectrometry, LC-MS = liquid chromatography-mass spectrometry, LC-MS/MS = liquid chromatography-tandem mass spectrometry, NL = neutral loss, PORD = cytochrome P450 Oxido-Reductase Deficiency, SIM = single ion monitoring, SLOS = Smith-Lemli-Opitz Syndrome, SPE = solid phase extraction, SRM = selected reaction monitoring, STSD = Steroi...

The total synthesis of three diastereomeric matrine natural products is reported. The 8-step synthesis commences with simple acyclic precursors, forms all 4 rings of the tetracyclic natural product framework, and forges 10 of the 20 covalent bonds of the target structure. A cross-conjugated triene is positioned at the core of an acyclic branched structure. This precursor collapses to the tetracyclic natural product framework through an orchestrated sequence of two separate intramolecular cycloadditions. A subsequent, late-stage hydrogenation is accompanied by strain-release redox epimerizations to deliver the three natural products. An unprecedented carba-analogue is prepared in the same way. Semisynthetic manipulations of matrine provide access to 10 additional natural products.

A general synthetic approach to molecular structures that are hybrids of tetraethynylethylene (TEE) and tetravinylethylene (TVE) is reported. The synthesis permits the controlled preparation of many previously inaccessible structures, including examples with different substituents on each of the four branching arms. Most substituted TVE−TEE hybrids are found to be significantly more robust compounds than their unsubstituted counterparts, enhancing the prospects of their deployment in conducting materials and devices. Their participation in pericyclic reaction cascades, leading to sp 3 -rich polycycles, is demonstrated. The utilization of TEE−TVE hybrids as building blocks for larger acyclic, through/cross-conjugated hydrocarbon frameworks is also established. Aryl-substituted TEEs, TVEs, and their hybrids are fluorescent, with some exhibiting aggregation-induced emission enhancement. The structural requirements are defined and explained, setting the scene for applications as fluorescent probes and organic light-emitting diodes.

The total synthesis of three diastereomeric matrine natural products is reported. The eight-step synthesis commences with simple acyclic precursors, forms all four rings of the tetracyclic natural product framework and forges ten of the twenty covalent bonds of the target structure. The chemical synthesis adopts an unprecedented strategy that encompasses both transform and stereochemical attributes. A cross-conjugated triene is positioned at the core of an acyclic branched structure, which collapses to the tetracyclic natural product framework through an orchestrated sequence of two intramolecular cycloadditions. A subsequent, late-stage hydrogenation is accompanied by strain-release redox epimerizations to deliver the three natural products. Semisynthetic manipulations of matrine provide access to ten additional natural products.