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Selective syntheses of leuconolam, leuconoxine, and mersicarpine alkaloids from a common intermediate through regiocontrolled cyclizations by Staudinger reactions†Electronic supplementary information (ESI) available: Experimental details and procedures, compound characterization data, copies of (1)H and (13)C NMR spectra for new compounds. See DOI: 10.1039/c4qo00312hClick here for additional data file.

Li Z, Geng Q, Lv Z, Pritchett BP, Baba K, Numajiri Y, Stoltz BM, Liang G - Org Chem Front (2015)

Bottom Line: Selective syntheses of leuconolam, leuconoxine, and mersicarpine alkaloids bearing distinctive core structures were achieved through Staudinger reactions using a common intermediate.In the key cyclization step, water functioned like a switch to control which core structure to produce.The chemistry allowed for selective syntheses of the group of alkaloids from a simple intermediate through straightforward chemical operations.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory and Institute of Elemento-organic Chemistry , Collaborative Innovation Center of Chemical Science and Engineering (Tianjin) , Nankai University , Tianjin 300071 , China . Email: lianggx@nankai.edu.cn.

ABSTRACT

Selective syntheses of leuconolam, leuconoxine, and mersicarpine alkaloids bearing distinctive core structures were achieved through Staudinger reactions using a common intermediate. In the key cyclization step, water functioned like a switch to control which core structure to produce. The chemistry allowed for selective syntheses of the group of alkaloids from a simple intermediate through straightforward chemical operations.

No MeSH data available.


Efforts in preparing optically active 12.
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sch5: Efforts in preparing optically active 12.

Mentions: With efficient racemic syntheses in hand, we took on an effort to produce optically active 12, thereby achieving formal asymmetric syntheses of these alkaloids (Scheme 5). Initially, we hoped diester 22 could undergo an efficient asymmetric allylic alkylation to construct enantioenriched quaternary lactone 23. We found that the reaction with diester 22 proceeded smoothly, but with disappointing enantioselectivity (81% ee). Eventually, we were able to generate optically active 12 from an N-benzyloxy imide 24, which could be readily prepared in 80% yield and 98% ee.23 Reduction of 24 with an excess of NaBH4 formed hydroxamic acid 25 with the desired free primary alcohol. The following acid-induced cyclization of 25 provided the desired lactone (–)-12 in 54% yield over 2 steps.


Selective syntheses of leuconolam, leuconoxine, and mersicarpine alkaloids from a common intermediate through regiocontrolled cyclizations by Staudinger reactions†Electronic supplementary information (ESI) available: Experimental details and procedures, compound characterization data, copies of (1)H and (13)C NMR spectra for new compounds. See DOI: 10.1039/c4qo00312hClick here for additional data file.

Li Z, Geng Q, Lv Z, Pritchett BP, Baba K, Numajiri Y, Stoltz BM, Liang G - Org Chem Front (2015)

Efforts in preparing optically active 12.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4333676&req=5

sch5: Efforts in preparing optically active 12.
Mentions: With efficient racemic syntheses in hand, we took on an effort to produce optically active 12, thereby achieving formal asymmetric syntheses of these alkaloids (Scheme 5). Initially, we hoped diester 22 could undergo an efficient asymmetric allylic alkylation to construct enantioenriched quaternary lactone 23. We found that the reaction with diester 22 proceeded smoothly, but with disappointing enantioselectivity (81% ee). Eventually, we were able to generate optically active 12 from an N-benzyloxy imide 24, which could be readily prepared in 80% yield and 98% ee.23 Reduction of 24 with an excess of NaBH4 formed hydroxamic acid 25 with the desired free primary alcohol. The following acid-induced cyclization of 25 provided the desired lactone (–)-12 in 54% yield over 2 steps.

Bottom Line: Selective syntheses of leuconolam, leuconoxine, and mersicarpine alkaloids bearing distinctive core structures were achieved through Staudinger reactions using a common intermediate.In the key cyclization step, water functioned like a switch to control which core structure to produce.The chemistry allowed for selective syntheses of the group of alkaloids from a simple intermediate through straightforward chemical operations.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory and Institute of Elemento-organic Chemistry , Collaborative Innovation Center of Chemical Science and Engineering (Tianjin) , Nankai University , Tianjin 300071 , China . Email: lianggx@nankai.edu.cn.

ABSTRACT

Selective syntheses of leuconolam, leuconoxine, and mersicarpine alkaloids bearing distinctive core structures were achieved through Staudinger reactions using a common intermediate. In the key cyclization step, water functioned like a switch to control which core structure to produce. The chemistry allowed for selective syntheses of the group of alkaloids from a simple intermediate through straightforward chemical operations.

No MeSH data available.