Enantiodivergent Total Syntheses of (+)- and (−)-Scopadulcic Acid A

Fox, Anthony; Li, b Chi; Marino, Carla; Overman, Larry E.

doi:10.1021/ja990404v

Cited by 141 publications

(71 citation statements)

References 71 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…[29][30][31][32][33][34][35] Since Ishizaki and Hoshino 24 reported the first addition of alkynylzinc reagents to aldehydes in 1994, some chiral ligands, such as N-methylephedrine, 19 sulfonamide alcohol, 36 BINOL and its derivatives, [20][21][22][23] have successfully been applied to this reaction in recent years. The amino alcohol ligand shows excellent enantioselectivity for the alkynylzinc addition to aliphatic aldehydes, and the BINOL catalyst shows excellent enantioselectivity for the alkynylzinc addition to aromatic aldehydes.…”

Section: Scheme 1 Reported Bifunctional Binol Derivativesmentioning

confidence: 99%

Bifunctional Enantioselective Ligands of Chiral BINOL Derivatives for Asymmetric Addition of Alkynylzinc to Aldehydes

Zou

Zheng

et al. 2008

Chin. J. Chem.

View full text Add to dashboard Cite

Four analogous binaphthyl compounds (R)-3a-3d containing (R)-3,3'-bis(2-pyridyl) groups were synthesized by the conjugation of (R)-2,2'-dimethoxy-1,1'-binaphthyl-3,3'-diboronic acid [(R)-2] with 2-bromopyridine, 2-bromo-5-methylpyridine, 2-chloro-4-fluoropyridine and 2-chloro-3-(trifluoromethyl)pyridine via Pd-catalyzed Suzuki reactions, respectively. The application of the four chiral ligands in combination with Et 2 Zn and Ti(Oi-Pr) 4 to the asymmetric addition of phenylacetylene to various aldehydes has been studied. The results show that (R)-3a and (R)-3b are not good catalysts for the alkynylzinc addition to aldehydes, (R)-3d shows good enantioselectivity only for the alkynylzinc addition to aliphatic aldehydes, and (R)-3c exhibits excellent enantioselectivity for phenylethynylzinc addition to both aromatic and aliphatic aldehydes. All the four chiral ligands produced the opposite configuration of the propargylic alcohols to that of the chiral ligands.

show abstract

Section: Scheme 1 Reported Bifunctional Binol Derivativesmentioning

confidence: 99%

Bifunctional Enantioselective Ligands of Chiral BINOL Derivatives for Asymmetric Addition of Alkynylzinc to Aldehydes

Zou

Zheng

et al. 2008

Chin. J. Chem.

View full text Add to dashboard Cite

show abstract

“…The precursor of 144 was the corresponding chlorohydrin and lithium naphthalenide the lithiating reagent [86], meanwhile intermediates 145 [112], 146 [113] and 147 [114] were prepared by iodine±lithium exchange by means of t-BuLi. All of them reacted with electrophiles to yield polyfunctionalized compounds, compound 146 being used in the synthesis of scopadulcic acid A.…”

Section: C-functionalized Alkyllithium Compoundsmentioning

confidence: 99%

Polyfunctional Lithium Organometallics for Organic Synthesis

Yus¹,

Foubelo²

2005

Handbook of Functionalized Organometallics

View full text Add to dashboard Cite

Multifunctional organic molecules can be achieved by reacting functionalized organolithium compounds [1] with electrophilic reagents, this fact makes these intermediates of relevant interest in synthetic organic chemistry [2]. Another remarkable fact concerning organolithium compounds, compared with other organometallic compounds is that they can be prepared following a great number of different methodologies [3]: hydrogen±lithium exchange (deprotonation), halogen±lithium exchange, transmetallation reactions, carbon±heteroatom bond cleavage and carbolithiation of multiple carbon±carbon bonds. However, the highly ionic character of the carbon±lithium bond [4] makes these compounds extremely reactive and also unstable, so the synthetic processes should be carried out in some cases under very mild reaction conditions.Regarding the stability of functionalized organolithium compounds, it depends mainly on three factors, the most important one being the compatibility of the functional group with the carbon±lithium bond, so in some cases the functionality should be protected. The hybridization of the carbon atom bonded to the lithium atom is also important, so sp derivatives are more stable than the corresponding sp 2 and these are more stable than the sp 3 ones as it happens to the corresponding carbanions. Finally, the relative position of the functionality and the carbanionic center is also relevant, probably the b-functionalized derivatives being the most unstable species due to the existence of two consecutive carbon atoms with opposite polarities, the b-elimination process to give an olefin is extremely favored. Stabilized organolithium compounds, such as lithium enolate intermediates [5], a-organolithium compounds bearing electron-withdrawing groups (RSO, RSO 2 , CN, NO 2 , etc.) and heteroatoms such as sulfur [6], selenium and phosphorus as well as functionalized aryllithium compounds will not be consider in depth in this chapter due to the limited length of this review.The following study is ordered based on the relative position of the functionality and the carbanionic center, as well as on the hybridization of that center.

show abstract

“…[2,3] Accordingly, much progress has been made in the asymmetric addition of terminal alkynes to aldehydes, which has been established as a reliable platform for the efficient synthesis of a wide array of chiral propargylic alcohols. [1,4] Various alkyne derivatives such as arylacetylene, alkylacetylene, ethynylcyclohexene, acetalacetylene, methyl propiolate, 1,3-diyne, and trimethylsilylacetylene have been used as the alkyne nucleophiles.…”

mentioning

confidence: 99%

“…Among the catalytic systems reported so far for the alkynylation of aldehydes, the amino-alcohol-Zn system is particularly noteworthy in terms of its operational simplicity and mild reaction conditions. The amino-alcohol-Zn catalytic system has attracted much attention since the pioneering contribution from Carreira and co-workers, who demonstrated that by using a combination of ZnA C H T U N G T R E N N U N G (OTf) 2 and Nmethylephedrine, the addition of terminal acetylenes to aldehydes afforded the desired products in high yields and enantioselectivities. [4b, 12] However, to the best of our knowledge, no impressive amino-alcohol-Zn system (except for Trosts dinuclear Zn catalyst) for the alkynylation of aldehydes with trimethylsilylacetylene has been reported so far, therefore a new, generally applicable procedure using amino-alcohol-Zn would still be highly desirable.…”

mentioning

confidence: 99%