Osmium, a group 8 d-block transition metal discovered in 1803 by the English chemist Smithson Tennant, is the rarest of the stable elements. Concentrations in the Earth’s crust are around 50 parts per trillion. The metal is found in nature uncombinrd or alloyed with its neighbour, iridium, in the alloys iridosmine or osmiridium. Around 500Kg
Written By: Dr John Studley
When approaching the synthesis of an aryl- or heteroaryl- amine most people would turn to a suitable transition metal (Pd, Cu or Ni) catalysed C-N cross-coupling reaction- most likely a Buchwald-Hartwig reaction, or, if this has limited success, Ullmann or Chan-Evans-Lam couplings.1 Photoredox approaches using aryloxy amides as a source of amidyl radicals began a trend
Xenon (Xe, Element 54) Xenon, from the Greek for ‘stranger’ is a colourless, odourless group 18 noble gas. Discovered in 1898 in London by William Ramsay, xenon is produced commercially by the fractional distillation of liquid air and is isolated as a by-product of the cryogenic production of oxygen and nitrogen. The concentration in the
Aryl- and heteroaryl- diazonium tetrafluoroborate salts, prepared by diazotization of an aniline in the presence of HBF4, are unique in that in many cases they are sufficiently stable to isolate. Thermal decomposition of these salts at elevated temperatures results in fluoro-dediazoniation and formation of the corresponding aryl or heteroaryl fluoride- the Balz-Schiemann reaction.1a,bRadiolabelled 18F compounds
Raltegravir (free base) Selective N- v’s O- alkylation of an amide can be challenging and somewhat unpredictable- the outcome being highly dependent on the structure of the substrate. A good example of this is the N-methylated pyrimidone intermediate (5) en route to Merck’s antiretroviral drug Raltegravir.1 Direct methylation of amide (4) (Figure 1) using MeI gives significant
Lithium (Li, Element 3) Lithium, first member of the group 1 alkali metals, was discovered in 1817 by Johan August Arfwedson. It’s been around since the dawn of (astronomical) time- both stable isotopes, Li6 and Li7, being among a small handful of elements created in the Big Bang.1Terrestrially its highly abundant in seawater (up to
Figure 1: Suzuki-Miyaura Coupling It’s a reaction that most organic chemists have run at some stage in their careers and is almost certainly in the running for the most widely used C-C bond forming reaction. First reported in 1979, the Suzuki-Miyaura cross-coupling between an organoboron nucleophile and an aryl halide electrophile is still ubiquitous in
Vanadium (V, Element 23) Vanadium, a group 5 transition metal, discovered in 1801 by Andres Manuel del Rio, occurs naturally as a component of vanadinite (Pb5(VO4)3Cl), one of the main industrial ores used as a source of the metal. Over 60 ores are known, with 70-80 thousand tonnes of ore mined globally each year, producing
Heterocyclic phosphonium salts- powerful intermediates for pyridine coupling:- I’ve always had a keen interest in phosphorus chemistry and have followed the work of the McNally group at Colorado state on heterocyclic phosphonium salts closely. In late 2016 a paper describing synthesis and application of the so called HetPhos salts for C4 (or C2) functionalisation of
Figure 1 I guess to qualify as a reagent of the month the material has to fulfil certain criteria and commercial availability, though not essential, is very desirable. N-((Methylsulfonyl)oxy)acetimiodyl chloride (henceforth known, at least by me, as Fier’s reagent) is now available to buy from Sigma Aldrich (CAS: 1433887-06-9). The compound is an air and
