Asymmetric Ring-Closing Metathesis

Alkyne cross metathesis Acyclic diene metathesis Asymmetric ring-closing metathesis Asymmetric ring-opening metathesis Cross metathesis... 

Asymmetric microbial acyloin condensation, 16 402 Asymmetric oxidation, 23 735 Asymmetric ring-closing metathesis (ARCM), 26 922... 

FIGURE 28.2 Substrates for asymmetric ring closing metathesis. 

Recently, chiral molybdenum catalysts such as 11 have been synthesized, giving access to asymmetric ring-closing metathesis [7]. Water-soluble variations of catalyst 10, like catalyst 12, perform metathesis in water or methanol [8], extending the scope of the reaction to substrates which are poorly soluble in organic solvents. 

Another interesting approach in asymmetric ring-closing metathesis is the catalytic enantiose-lective desymmetrization of achiral starting materials [21 ] (61 62). Starting with achiral material... 

Figure 3 Chiral molybdenum alkylidene complexes used in asymmetric ring closing metathesis polymerization...

A 3-phospholene oxide, a 1,2,3,6-tetrahydrophosphinine oxide and a 2,3,4,7-tetrahydrophosphepine oxide were prepared by a novel molybdenum-catalyzed asymmetric ring closing metathesis (Scheme 2). ... 

Finally, there is a report on Mo-catalysed asymmetric ring closing metathesis (ARCM) for the enantioselective desymmetrisation of prochiral phosphinates and phosphine oxides (Scheme 6.53). This constitutes the first example where ARCM is used to prepare chiral compounds with a heteroatom as stereogenic centre. 

On the basis of the original studies [111-113], the DoM-cross-coupHng sequence represents a significant entry into chiral binaphthol (BINOL) and achiral biphenol (BIPOL) ligands (Table 14.18) [111-119], which are outside the scope of this review but are widely used for enantioselective reactions, for example, Et2Zn addition to aromatic aldehydes, the Mannich-type reactions, and the Diels-Alder as well as asymmetric ring-closing metathesis (ARCM) reactions. 

Scheme 3.4 Asymmetric ring-closing metathesis using C,-symmetric NHCs.

Sattely ES, Cortez GA, Moebius DC, Schrock RR, Hoveyda AH. Enantioselective synthesis of cyclic amides and amines through Mo-catalyzed asymmetric ring-closing metathesis. J. Am. Chem. Soc. 2005 127 8526-8533. 

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