Nysted reagent

The Nysted reagent, cyclo-dibromodi- x-methylene( x-tetrahydrofuran)trizinc, is used for the olefmation of ketones and aldehydes. 

Name Reactions A Collection of Detailed Mechanisms and Synthetic Applications, DOI 10.1007/978-3-319-03979-4 197, Springer International Publishing Switzerland 2014 

Example 1, The Wittig reagent opened the laetone OMOM 

Name Reactions, 4th ed., DOI 10.1007/978-3-642-01053-8 184, Springer-Verlag Berlin Heidelberg 2009 

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The cycloadduct of an a,a -dioxo-thioketone with antracene,84 treated at low temperature with the Nysted reagent and TiCl4, transforms a ketone group to the corresponding methylenic group. This product is thermically decomposed via retro Diels-Alder reaction into the unstable a, p-unsaturated-a -oxo derivative (Scheme 10). 

Not only a zinc-copper couple, but also a zinc-lead couple forms a gem-dimetal species from diiodomethane, according to the 1975 Nysted patent5. He also insisted that treatment of dibromethane with a zinc-lead couple in THF at 80 °C forms a characteristic gem-dizinc species 1 (equation 3). However, there was no further evidence concerning the structure except H NMR data, which was not enough for the complete structural determination. The obtained compound was definitely a gem-dizinc species, but the written structure 1 was not fully characterized. The white solid 1 is obtained as a dispersion in THF, and does not dissolve in DMF and DMI (l,3-dimethyl-2-imidazolidinone). This THF dispersion is commercially available from Aldrich Co. as Nysted reagent. Nysted also showed that this dizinc compound is effective for the methylenation of a-hydroxy ketone moiety in steroid derivatives5. 

Aldehydes are methylenated by bis(iodozincio)methane (3) without the mediation of titanium salt. Commercially available Nysted reagent 1 is also effective for this transformation in this case, the addition of a catalytic amount of BF3 OEt2 improved the yield (Table l)31a c. 

TABLE 1. Methylenation of aldehydes with bis(iodozincio)methane (3) and Nysted reagent (1) ... 

Nysted reagent was weighed according to the structure 1, shown in the original patent9. (1.0 mmol), dizinc (1.0 or 2.0 mmol) and additive were mixed in THF. 

The Nysted reagent [L. N. Nysted, US Patent 3 865 848 (1975) Chem. Abstr., 83, 10406q (1975)] is commercially available from Aldrich Co. 

Nysted used a Zn reagent (Nysted reagent, 4.100) for the methylenation of ketones and aldehydes ... 

Bis(bromozinciomethyl)zinc-tetrahydrofuran complex, Nysted reagent. 

Methylenation of carbonyl compounds. The Nysted reagent (BrZnCH2)2Zn(thf) is... 

The Nysted reagent (696) 2 jg commercially available, and it reacts with aldehydes or ketones in the presence of BF3 etherate to give an alkene. Reaction with 2-phenylpropanal, for example, gave an 82% yield of 697.5 3 The Takai reactionist uses MeCHl2 in the presence of CrCl2 to generate the alkene. An example is taken from Chida s synthesis of pironetin in which aldehyde 698 was converted to 699 in 74% yield as an 11 1 mixture of (ElZ) isomers.iSS... 

Other references related to the Nysted reagent are cited in the literature. ... 

Preferential catalytic hydrogenation of the C(4)-C(6) double bond of 26.67, followed by methylenation with the Nysted reagent (Aldrichimica Acta 26, 14 (1993), completed the synthesis of lactarane diester 26.69 which afforded the crystalline target compound 11.3 in two additional steps. 

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