Michael Wittig domino reactions

A catalytic triple domino Michael-aldol-oxa-Michael reaction of acetaldehyde with ( -2-(2-nitrovinyl)phenols catalyzed by (R)-2- diphenyl [(trimethylsilyl)oxy] methyl pyrrolidine followed by a sequential one-pot Wittig, Michael/Wittig-Horner reactions with PPh3=CHC02Et was applied to the asymmetric synthesis of polyfunctionalized chromans (14EJO3076). 

Scheme 7.7 Domino Michael-Wittig reaction catalysed by chiral amine catalysis and copper catalysis.

Scheme 2.48. Results of the chiral auxiliary supported domino Michael addition/ Wittig reactions.

The following example completes the section of threefold anionic domino processes initiated by a SN-type reaction. As discussed earlier in Section 2.2, the reaction of a five-membered cyclic phosphonium ylide with enones, a, 3-unsaturated esters, and a, 3-unsaturated thioesters provides cycloheptene or hydroazulene derivatives in a domino Michael/intramolecular Wittig reaction. This sequence... 

The final example of a domino process under high pressure, to be discussed in this chapter, is a combination of a Horner-Wittig-Emmons (HWE) reaction with a Michael addition developed by Reiser and coworkers [5]. Hence, reaction of a mixture of an aldehyde such as 10-18, a phosphonate 10-19 and a nucleophile 10-20 in the presence of triethylamine at 8 kbar led to 10-21. By this method, (3-amino esters, 3-thio esters and 3-thio nitriles can be prepared in high yield (Scheme 10.4). Many of these transformations do not occur under standard conditions, thereby underlining the importance of high pressure in organic chemistry. 

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