Aldol reactions 2- trimethylsilyloxy-1,3-butadiene

Triphenylphosphine-Diethyl azodicar-boxylate-Lithium halides, 332 Mukaiyama aldol reaction 1-Methoxy-l, 3-bis(trimethylsilyloxy)-l, 3-butadiene, 178 Tin(II) chloride, 298 Titanium(IV) chloride, 304 Trityl perchlorate, 339 Murahashi reaction N,N-Methylphenylaminotributylphos-phonium iodide, 191... 

Reaction of aldehydes with l-methoxy-3-trimethylsilyloxy-l,3-butadiene catalyzed by 1 provides an aldol as the major product. 

Scheme 9.51. The result of the copper-oxazohne-derived catalyst to promote the reaction between 2-benzyloxyacetaldehyde (2-benzyloxyethanal, C6HSCH2OCH2CHO) and l-methoxy-l,3-bis(trimethylsilyloxy)-13-butadiene. The reaction results in a 97% yield of methyl (35, 55 )-6-benzyloxy-3,5-dihydroxyhexanoate, the vinylogous aldol product (after hydrolysis). See Evans,D. Woerpel,K.A. Scott,M. I.ylngeH. Chem. Int. (i., 1992,57,430.

In synthesis of isotetronic acid derivatives, aldol-type reactions of 1,2-dicarbonyl substrates including oxalyl chloride and pyruvates are used as powerful mefhodologies. For instance, Langer et al. reported systematic investigations on such reaction of oxalyl chloride 21 wifh l,3-bis(trimethylsilyloxy)-l,3-butadienes 22 or 24 as masked dianion equivalenfs (Scheme 10) [21]. By using a catalytic amoxmt of MesSiOTf, y-lactone formation smoothly occurred to yield the lactones (E)-23 or (Z)-25, respectively. This methodology is also effective for the synthesis of medium-sized bicyclic y-bufenolides such as 25c [22]. 

---