Total synthesis of rapamycin via a novel titanium-mediated aldol macrocyclization reaction

Hayward, Cheryl M.; Yohannes, Daniel; Danishefsky, Samuel J.

doi:10.1021/ja00073a083

Cited by 111 publications

(32 citation statements)

References 4 publications

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“…Synthesis of homoallylic alcohols via Barbier-type carbonyl allylation is of great importance, since the homoallylic alcohols are versatile subunits for manufacturing many useful biologically active molecules including polyether, macrolides, and antibiotics. 301 The Barbier-type carbonyl allylation has been realized mainly by homogeneous organometallic catalysis. 302,303 The Barbiertype carbonyl allylation in aqueous media was realized on metallic In powder in 1991.…”

Section: 77mentioning

confidence: 99%

Synthesis and catalysis of chemically reduced metal–metalloid amorphous alloys

et al. 2012

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Amorphous alloys structurally deviate from crystalline materials in that they possess unique short-range ordered and long-range disordered atomic arrangement. They are important catalytic materials due to their unique chemical and structural properties including broadly adjustable composition, structural homogeneity, and high concentration of coordinatively unsaturated sites. As chemically reduced metal-metalloid amorphous alloys exhibit excellent catalytic performance in applications such as efficient chemical production, energy conversion, and environmental remediation, there is an intense surge in interest in using them as catalytic materials. This critical review summarizes the progress in the study of the metal-metalloid amorphous alloy catalysts, mainly in recent decades, with special focus on their synthetic strategies and catalytic applications in petrochemical, fine chemical, energy, and environmental relevant reactions. The review is intended to be a valuable resource to researchers interested in these exciting catalytic materials. We concluded the review with some perspectives on the challenges and opportunities about the future developments of metal-metalloid amorphous alloy catalysts.

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Section: 77mentioning

confidence: 99%

Synthesis and catalysis of chemically reduced metal–metalloid amorphous alloys

et al. 2012

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“…The combined extracts were washed with brine, dried (MgSO 4 ) and concentrated in vacuo. The residue was purified by flash column chromatography (EtOAc:hexanes, gradient 1:1 to 2:1) to afford the desired alcohol 26 (1.13 g, 71%) as a colorless oil: IR (film) 2901,2341,1718,1675,1456,1394,1368,1170,1123,669 62 (4H, m), 1.47 (9H, s), 1.43-1.33 (1H, m); 13 C NMR (75 MHz, CDCl 3 ) δ 171. 5,170.6,145.1,136.2,130.4,130.0,129.2,128.2,104.0,74.5,73.7,64.7,60.7,59.7,59.5,54.3,53.8,52.7,45.5,35.1,28.9,28.1,25.4,20.1;HRMS (APCI+) …”

Section: -(22-dimethoxyethyl)-7a-(1-hydroxy-2-methoxyethyl)-7-oxo-6mentioning

confidence: 99%

Construction of an Advanced Tetracyclic Intermediate for Total Synthesis of the Marine Alkaloid Sarain A

2006

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In work directed towards a total synthesis of the marine alkaloid sarain A (1), the advanced intermediate 54, containing all the key elements and the seven stereogenic centers of sarain A, has been successfully synthesized from bicyclic lactam 4, previously prepared via an intramolecular stereospecific [3 + 2]-azomethine ylide dipolar cycloaddition. Intermediate lactam 4 could be efficiently converted to N-Boc derivative 12. Introduction of a two carbon fragment into lactam 12 which eventually becomes the C-7′,8′ syn diol of the "eastern" ring was then achieved by C-acylation of the corresponding enolate with methoxyacetyl chloride followed by a highly stereoselective ketone reduction with Zn(BH 4 ) 2 to afford alcohol 16. Intermediate 16 has the incorrect C-7′ relative stereochemistry for sarain A, but this problem was conveniently remedied by inverting the C-7′ center via an intramolecular Ohfune-type cyclization of the silyl carbamate derived from Boc mesylate 27 to produce the key cyclic carbamate 28. It was then possible to convert acetal 28 to allylsilane 32 followed by cyclization to the alkaloid tricyclic core 33 via an allylsilane/N-sulfonyliminium ion cyclization. Formation of the "western" macrocyclic ring has been successfully addressed using functional group handles at C-3′ and N-1′ on the tricyclic core via a ring-closing olefin metathesis (RCM) strategy with the second-generation Grubbs ruthenium catalyst to produce intermediate macrolactam 47. A chelation-controlled addition of ethynylmagnesium bromide to advanced aldehyde 51 afforded a single diastereomeric adduct 53 which is tentatively assigned to have the correct C-7′,8′ syn diol stereochemistry. This adduct could be rearranged to the conveniently protected amino carbonate 54 which is set up for construction of the remainder of the "eastern" ring of sarain A.

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“…When the ratio of 2a/9a/Sn is fixed at 1/1.5/2.5, the yield of 10a increases with increasing allylic bromide, but 4 equiv. is a reasonable amount (Table 3, entries [15][16][17][18]. The reason for the use of excess allylic bromide is that part of it would be hydrolyzed during the reaction.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of homoallylic amines and acylhydrazides by tin powder‐promoted multicomponent one‐pot allylation reactions

Huang

Wang

et al. 2016

Applied Organom Chemis

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An efficient process for the synthesis of homoallylic amines and N′-homoallylic hydrazides is developed from the one-pot reaction of carbonyl compounds, amines or N-acylhydrazines, allyllic bromide and tin powder using water as solvent. N-Acylhydrazines are found to be more reactive than amines in these processes. They can react not only with aldehydes but also with ketones to give the corresponding N′-homoallylic hydrazides.

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Total synthesis of rapamycin via a novel titanium-mediated aldol macrocyclization reaction

Cited by 111 publications

References 4 publications

Synthesis and catalysis of chemically reduced metal–metalloid amorphous alloys

Synthesis and catalysis of chemically reduced metal–metalloid amorphous alloys

Construction of an Advanced Tetracyclic Intermediate for Total Synthesis of the Marine Alkaloid Sarain A

Synthesis of homoallylic amines and acylhydrazides by tin powder‐promoted multicomponent one‐pot allylation reactions

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