Allene epoxidation. Efficient synthesis and synthetic conversions of 1,4-dioxaspiro[2.2]pentanes

“…7c The enantioenriched propargyl alcohol 16 was prepared according to literature procedure and converted to the allene 17 (Scheme 2). 10 The synthesis of the DASP 19 from the alcohol 16a resulted in no degradation in the enantiopurity, and a simple recrystallization enhanced the er to 96:4.…”

Section: Resultsmentioning

confidence: 99%

“…Pioneering studies by the Crandall and Williams groups have demonstrated that bis-epoxidation of an allene to a spirodiepoxide (SDE) can be followed by elegant transformations of these highly reactive intermediates to 1,2,3-trioxygenated triads and other motifs. 7 More recently, the Williams group has greatly expanded the usefulness of spirodiepoxides by showcasing how allene epoxidation can be used in the synthesis of a number of complex natural products, including epoxomicin, psymberin, pectenotoxin 4, and the erythronolides. 7d–g However, the corresponding aziridination chemistry was not explored, despite the potential for facile access to densely functionalized and enantioenriched vicinal diamines.…”

Section: Introductionmentioning

confidence: 99%

“…7 More recently, the Williams group has greatly expanded the usefulness of spirodiepoxides by showcasing how allene epoxidation can be used in the synthesis of a number of complex natural products, including epoxomicin, psymberin, pectenotoxin 4, and the erythronolides. 7d–g However, the corresponding aziridination chemistry was not explored, despite the potential for facile access to densely functionalized and enantioenriched vicinal diamines.…”

Section: Introductionmentioning

confidence: 99%

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1,4-Diazaspiro[2.2]pentanes as a Flexible Platform for the Synthesis of Diamine-Bearing Stereotriads

et al. 2012

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Nitrogen-containing stereotriads occur in a number of biologically active compounds, but general and flexible methods to access these compounds are limited mainly to the manipulation of chiral olefins. An alternative approach is to employ a highly chemo-, regio-, and stereocontrolled allene oxidation that can install a new carbon–heteroatom bond at each of the three original allene carbons. In this paper, an intramolecular/intermolecular allene bis-aziridination is described that offers the potential to serve as a key step for the construction of stereotriads containing vicinal diaminated motifs. The resultant 1,4-diazaspiro[2.2]pentane (DASP) scaffolds contain two electronically differentiated aziridines that undergo highly regioselective ring-openings at C1 with a variety of heteroatom nucleophiles to give chiral N,N-aminals. Alternatively, the same DASP intermediate can be induced to undergo a double ring opening reaction at both C1 and C3 to yield vicinal diaminated products corresponding to formal ring opening at C3. The chirality of a propargyl alcohol is easily transferred to the DASP with good fidelity, providing a new paradigm for the construction of enantioenriched nitrogen-containing stereotriads.

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“…1,4-dioxaspiro[2.2]pentanes did not find utility in more synthetically useful scenarios until two decades later primarily due to the lack of efficient, neutral, and mild oxidizing reagents 37,38. The advent of dimethyl dioxirane by Murray and co-workers provided a more general synthesis of the 1,4-dioxaspiro[2.2]pentanes (Scheme 18).…”

Section: 1 4-dioxaspiro[22]pentanesmentioning

confidence: 99%