A novel stereoselective synthesis of (−)-β-conhydrine from (R)-2,3-O-cyclohexylidine glyceraldehyde

Venkataiah, Mallam; Fadnavis, Nitin W.

doi:10.1016/j.tet.2009.06.060

Cited by 18 publications

(4 citation statements)

References 37 publications

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“…Fadnavis and Venkatiah successfully achieved the stereoselective synthesis of (-)-β-conhydrine, starting from Dmannitol (Scheme 6). 18 Aldehyde 22, derived from mannitol, 19 was subjected to Grignard reaction to give 23 diastereoselectively. The alcohol 23 was converted into key requisite imine 24 using classical synthetic steps.…”

Section: Chiral Pool Methodsmentioning

confidence: 99%

Conhydrine: An Account of Isolation, Biological Perspectives and Synthesis

2014

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Conhydrine is a naturally occurring 2-substituted piperidine alkaloid from the plant Conium maculatum L that exists in four different forms and is known for its high toxicity. This article focuses on the synthesis of conhydrine as its medicinal applications are limited due to its high toxicity. The various asymmetric methods developed for the synthesis of conhydrine are classified based on the methodology: the chiral pool method, the chiral auixiliary method, and asymmetric catalysis. A brief overview of the complete synthetic coverage of conhydrine in different isomeric forms is given.

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Section: Chiral Pool Methodsmentioning

confidence: 99%

Conhydrine: An Account of Isolation, Biological Perspectives and Synthesis

2014

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“…58 As a result, stereochemical models such as the Felkin− Anh model may operate, so there may not be the same unpredictability or loss of stereoselectivity as observed with ketones and aldehydes. For example, addition of allylmagnesium bromide to chiral α-alkoxy aldimine 45 proceeded with high diastereoselectivity (Scheme 18 59 ), as compared to the additions of allylmagnesium reagents to α-alkoxy aldehydes and ketones (as illustrated in Scheme 3).…”

Section: Additions To Iminesmentioning

confidence: 99%

“…As discussed in section 4.1, the rate acceleration observed for additions to α-alkoxy ketones was essential for diastereoselectivity because these systems operate under Curtin− Hammett control, where the majority of the product is formed through the lower-energy, chelated transition state. If rate acceleration were not present, the chelated transition state would no longer be favored, so addition could occur to any of the many forms of the aldehyde in solution (i.e., not complexed to RMgX (58), complexed to RMgX but not chelated (59), and chelated to RMgX (60), as illustrated in Scheme 24), resulting in low stereoselectivity. 22 It is possible that, because reactions of allylmagnesium halides with α-alkoxy ketones are not chelation-controlled due to the high rate constants associated with addition reactions, reactions involving all organomagnesium halides with α-alkoxy aldehydes are generally not amenable to chelation control due to the higher reactivity of aldehydes compared to ketones.…”

Section: Additions Of Allylmagnesium Reagents To α-Substituted Carbon...mentioning

confidence: 99%

“…For example, additions of allylmagnesium reagents to simple imines proceed with chelation-controlled diastereoselectivity, as noted earlier (Scheme 18, section 2.5). 59 This observation, however, does not seem to be general. Additions to imine 890 occurred with high diastereoselectivity for most organomagnesium reagents (Scheme 355).…”

Section: Mechanism Of Additions Of Allylmagnesium Reagents To the Car...mentioning

confidence: 99%

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Reactions of Allylmagnesium Reagents with Carbonyl Compounds and Compounds with C═N Double Bonds: Their Diastereoselectivities Generally Cannot Be Analyzed Using the Felkin–Anh and Chelation-Control Models

et al. 2020

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This review describes the additions of allylmagnesium reagents to carbonyl compounds and to imines, focusing on the differences in reactivity between allylmagnesium halides and other Grignard reagents. In many cases, allylmagnesium reagents either react with low stereoselectivity when other Grignard reagents react with high selectivity, or allylmagnesium reagents react with the opposite stereoselectivity. This review collects hundreds of examples, discusses the origins of stereoselectivities or the lack of stereoselectivity, and evaluates why selectivity may not occur and when it will likely occur. CONTENTS 4.2.5. Additions to β-Substituted Aldehydes 4.2.6. Additions to Aldehydes with Distant Chelating Groups 4.3. Additions to Cyclic Ketones 4.3.1. Alkoxy-Substituted Cyclic Ketones 4.3.2. Additions to Alkoxy-Substituted Five-Membered-Ring Ketones 4.3.3. Additions to Alkoxy-Substituted Four-Membered-Ring Ketones 4.4. Additions of Allylmagnesium Halides to Cyclic Hemiacetals 5. Diastereoselectivity of Reactions of Allylmagnesium Reagents with Carbonyl Compounds by Felkin−Anh Control 5.1. Felkin−Anh Stereoselectivity 5.2. Additions to α-Chiral Acyclic Ketones 5.3. Additions to Chiral Exocyclic Ketones and Aldehydes 5.4. Additions of Allylmagnesium Halides to Chiral Cyclic Ketones Controlled by Felkin−Anh Selectivity 5.5. Additions of Allylmagnesium Halides to Chiral Acyclic Aldehydes 6. Diastereoselectivity of Reactions with Carbonyl Compounds by Steric Approach Control 6.1. Steric Approach Control and Stereoselectivity

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Olefin Ring‐Closing Metathesis

Yet

2016

Organic Reactions

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The olefin ring‐closing metathesis reaction catalyzed by ruthenium and molybdenum complexes has been employed in the syntheses of carbocycles, heterocycles, supramolecular compounds, and in tandem metathesis reactions. Chiral ruthenium and molybdenum catalysts have provided high enantiomeric and diastereomeric excesses in ring‐closing metathesis reactions. Many of the unsuccessful medium‐ and large‐sized ring formations which were unsuccessful by traditional methods, such as the intramolecular Wittig, Horner–Wadsworth–Emmons, and Julia–Kocienski reactions, can now be formed by olefin ring‐closing metathesis reactions. Ring‐closing metathesis has been a key step and sometimes the only successful method for the synthesis of numerous natural products and drug discovery targets. The objective of this chapter is to provide an updated, comprehensive coverage of the literature of the olefin ring‐closing metathesis reaction and related processes. Key mechanistic points are summarized.

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A novel stereoselective synthesis of (−)-β-conhydrine from (R)-2,3-O-cyclohexylidine glyceraldehyde

Cited by 18 publications

References 37 publications

Conhydrine: An Account of Isolation, Biological Perspectives and Synthesis

Conhydrine: An Account of Isolation, Biological Perspectives and Synthesis

Reactions of Allylmagnesium Reagents with Carbonyl Compounds and Compounds with C═N Double Bonds: Their Diastereoselectivities Generally Cannot Be Analyzed Using the Felkin–Anh and Chelation-Control Models

Olefin Ring‐Closing Metathesis

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