Zur Kenntnis der Pseudojononsynthese nach Kimel & Sax

Abstract

In the synthesis of pseudoionone by pyrolysis of dehydro‐linalyl‐acetoacetate (Kimel & Sax, US‐Pat. 2 661 368) an isomeric ketone is formed, the structure of which has been elucidated by degradation to d,l‐puleganic acid.

Saucy–Marbet rearrangements of alkynyl halides in the synthesis of highly enantiomerically enriched allenyl halides

“…With the exception of diastereosel ective examples,9,10 for axially chiral allenyl halides such as 2 , the level of enantiomeric enrichment was at best modest even when employing known conditions starting from mesylation of optically pure propargyl alcohols (R) - 1 and (S)- 1 1,2,11,12. Our interest13 in both the Saucy-Marbet rearrangement for the synthesis of chiral allenes9,14–16 and reactivities of alkynyl halides such as 5 17,18 prompted us to explore the synthesis of en antiomerically pure allenyl halides 7 by uniting the two concepts 19. We communicate here the concept of employing a stereospecific Saucy-Marbet rearrangement of alkynyl halides in the synthesis of highly enantiomerically enriched allenyl halides.…”

Highly Stereoselective Saucy−Marbet Rearrangement Using Chiral Ynamides. Synthesis of Highly Substituted Chiral Homoallenyl Alcohols

“…Ynamides are becoming attractive building blocks in organic synthesis. − We have been investigating reactivities of ynamides 12-15 and have demonstrated that chiral ynamides are useful in a stereoselective Ficini−Eschenmoser−Claisen rearrangement. , Given the power of the [3,3]-sigmatropic rearrangement in organic synthesis, we explored the utility of ynamides 1 in a stereoselective Saucy−Marbet rearrangement, − an appealing entry to chiral allenes (Figure ). Although Saucy and Marbet 18a first reported the utility of propargyl alcohols in Claisen-type rearrangements in 1958, there was just one account 19 describing stereochemical issues surrounding this rearrangement using optically enriched propargyl alcohols.…”

“…We quickly established the feasibility of Saucy−Marbet rearrangement using chiral ynamides (Scheme ) . Reactions of ynamide 7 with ( S )- and ( R )- 8 using PNBSA at 100 °C gave allenes 9 22 and 10 in 55 and 51% yields, respectively, as single diastereomers, suggesting excellent chirality transfer from chiral alcohols to the allenic axial center. 18d,

1

…”

Ynamides: A Modern Functional Group for the New Millennium

“…This research was later expanded upon with the first example of a Saucy-Marbet139 rearrangement of chiral ynamides with chiral propargyl alcohols140 (Scheme 145). After addition of the alcohol to give either 548 (matched) or 550a (mismatched), the resulting yne-enamides undergo a concerted [3,3]-sigmatropic rearrangement.…”