118487-18-6Relevant academic research and scientific papers
A reductive cyclization approach to attenol A
La Cruz, Thomas E.,Rychnovsky, Scott D.
, p. 2602 - 2611 (2007/10/03)
A reductive cyclization strategy was applied to the synthesis of attenol A. This nontraditional approach to the spiroacetal structure illustrated several advantages of the reductive cyclization methodology. The attenol A core was formed in a carbon-carbon bond coupling that gave rise to a previously inaccessible spiroacetal epimer, a new method to synthesize thioketene acetals from a phenyl sulfone was realized, and the configurational stability of a nonanomeric spiroacetal was evaluated. A minor byproduct in the reductive cyclization reaction was identified that for the first time allowed direct evaluation of the stereoselectivity in a reductive cyclization of a dialkyloxy alkyllithium reagent.
2-Amino Ketene S,S-Acetals as α-Amino Acid Homoenolate Equivalents. Synthesis of 3-Substituted Prolines and Molecular Structure of 2-(N-Pivaloylpyrrolidin-2-ylidene)-1,3-dithiane
Moss, William O.,Jones, Annette C.,Wisedale, Richard,Mahon, Mary F.,Molloy, Kieran C.,et al.
, p. 2615 - 2624 (2007/10/02)
Allylic deprotonation of the heterocyclic 2-amino ketene S,S-acetal 8a, followed by regioselective γ-alkylation reaction of the resulting organolithium 10 (a proline homoenolate equivalent) with electrophiles, leads to adduct 11.Controlled hydrolytic cleavage of 11 gives a series of 3-substituted prolines, including the conformationally-constrained aspartate and glutamate derivatives, 14e and 14f respectively.The bicyclic thiolactam 18 has been prepared in an attempt to provide an asymmetric variant of organolithium 10 but efforts to generate the requisite ketene N,S-acetal 19 were unsuccessful.Extension of the ketene S,S-acetal chemistry to other ring sizes has been examined within the context of substituted azetidine-2-carboxylates.Condensation of the protected amino ester 20 with AlMe3-HS(CH2)3SH was complicated, however, by the reactivity of the four-membered ring and led to the ring-opened adduct 24, with none of the required ketene S,S-acetal 22 being observed.
Preparation and Reactions of Some Cyclic Orthoester Derivatives
Crich, David,Ritchie, Timothy J.
, p. 2319 - 2328 (2007/10/02)
Deprotonation of the alkoxysulphone (5) followed by quenching with diphenyl disulphide yields the dithioorthoester (6) and not the expected ketene monothioacetal (7).Attempts at orthoester exchange of (6) with decanol with a variety of reagents lead to ring opened products.Quenching of the anion derived from (5) with sulphuryl chloride or bromine leads respectively to the chloride (19) and bromide (20).Solvolysis of these halides leads to formation of sulphinate esters.
