190315-22-1

Upstream product

• 19493-09-5 Methylenetriphenylphosphorane 
• 121651-02-3 (2S,3R)-2-formyl-3-phenyloxirane 
• 107-02-8 acrolein 
• 556-56-9 allyl iodid 
• 100-52-7 benzaldehyde 
• 2065-66-9 methyl-triphenylphosphonium iodide 
• 98819-68-2 3-phenyl-(2R,3R)-oxiran-2-ylmethanol 
• 4407-36-7 (2E)-3-phenyl-2-propen-1-ol 
• 100-51-6 benzyl alcohol 
• 100-39-0 benzyl bromide 

Downstream Products

• 190277-48-6 (+)-(S)-2-phenyl-but-3-en-1-ol 
• 473980-85-7 (2Z,5E)-(S)-7-Hydroxy-7-phenyl-hepta-2,5-dienoic acid methyl ester 
• 33442-47-6 (S)-2-phenylbutan-1-ol 

Relevant academic research and scientific papers

Asymmetric synthesis of trans-disubstituted aryl-vinyl epoxides: A p-methoxy effect

It was found that trans-aryl-vinyl epoxides could be synthesized with 77-100% conversion from conjugated aldehydes (which could also behave as Michael acceptors and lead to cyclopropanes) and chiral sulfonium salts with ee's ranging from 95 to 100%. When a p-methoxy group was present on the arylsulfonium salt, the epoxide was the sole product whatever the solvent. (C) 2000 Elsevier Science Ltd.

Practical and highly selective sulfur ylide-mediated asymmetric epoxidations and aziridinations using a cheap and readily available chiral sulfide: Extensive studies to map out scope, limitations, and rationalization of diastereo- and enantioselectivities

The chiral sulfide, isothiocineole, has been synthesized in one step from elemental sulfur, γ-terpinene, and limonene in 61% yield. A mechanism involving radical intermediates for this reaction is proposed based on experimental evidence. The application of isothiocineole to the asymmetric epoxidation of aldehydes and the aziridination of imines is described. Excellent enantioselectivities and diastereoselectivities have been obtained over a wide range of aromatic, aliphatic, and α,β-unsaturated aldehydes using simple protocols. In aziridinations, excellent enantioselectivities and good diastereoselectivities were obtained for a wide range of imines. Mechanistic models have been put forward to rationalize the high selectivities observed, which should enable the sulfide to be used with confidence in synthesis. In epoxidations, the degree of reversibility in betaine formation dominates both the diastereoselectivity and the enantioselectivity. Appropriate tuning of reaction conditions based on understanding the reaction mechanism enables high selectivities to be obtained in most cases. In aziridinations, betaine formation is nonreversible with semistabilized ylides and diastereoselectivities are determined in the betaine forming step and are more variable as a result.

Stereoselective synthesis of the styryllactones, 7-epi-goniodiol and leiocarpin A, isolated from Goniothalamus leiocarpus

Two novel styryllactones, 7-epi-goniodiol and leiocarpin A, isolated from Goniothalamus leiocarpus, were stereoselectively synthesized in a short and efficient route from cinnamyl alcohol based on the asymmetric epoxidation and the palladium-catalyzed cross-coupling of vinyl epoxide with vinyltributylstannane.

Sulfur-ylide-mediated synthesis of functionalized and trisubstituted epoxides with high enantioselectivity; Application to the synthesis of CDP-840

Benzyl and substituted allyl sulfonium salts react with a broad range of simple and functionalized aldehydes and ketones to give epoxides with high diastereoselectivity and high enantioselectivity (see scheme). The process has been applied to a short synthesis of the phosphodiesterase-IV inhibitor CDP-840. R1, R2 = hydrogen, alkyl, alkenyl, alkynyl, aryl, or pyridyl.

A new protocol for the in situ generation of aromatic, heteroaromatic, and unsaturated diazo compounds and its application in catalytic and asymmetric epoxidation of carbonyl compounds. Extensive studies to map out scope and limitations, and rationalization of diastereo- and enantioselectivities

A variety of metalated tosylhydrazone salts derived from benzaldehyde have been prepared and were reacted with benzaldehyde in the presence of tetrahydrothiophene (THT) (20 mol %) and Rh2(OAc)4 (1 mol %) to give stilbene oxide. Of the lithium, sodium, and potassium salts tested, the sodium salt was found to give the highest yield and selectivity. This study was extended to a wide variety of aromatic, heteroaromatic, aliphatic, α,β-unsaturated, and acetylenic aldehydes and to ketones. On the whole, high yields of epoxides with moderate to very high diastereoselectivities were observed. A broad range of tosylhydrazone salts derived from aromatic, heteroaromatic, and α,β-unsaturated rated aldehydes was also examined using the same protocol in reactions with benzaldehyde, and again, good yields and high diastereoselectivities were observed in most cases. Thus, a general process for the in situ generation of diazo compounds from tosylhydrazone sodium salts has been established and applied in sulfur-ylide mediated epoxidation reactions. The chiral, camphor-derived, [2.2.1] bicyclic sulfide 7 was employed (at 5-20 mol % loading) to render the above processes asymmetric with a range of carbonyl compounds and tosylhydrazone sodium salts. Benzaldehyde tosylhydrazone sodium salt gave enantioselectivities of 91 ± 3% ee and high levels of diastereoselectivity with a range of aldehydes. However, tosylhydrazone salts derived from a range of carbonyl compounds gave more variable selectivities. Although those salts derived from electron-rich or neutral aldehydes gave high enantioselectivities, those derived from electron-deficient or hindered aromatic aldehydes gave somewhat reduced enantioselectivities. Using α,β-unsaturated hydrazones, chiral sulfide 7 gave epoxides with high diastereoselectivities, but only moderate yields were achieved (12-56%) with varying degrees of enantioselectivity. A study of solvent effects showed that, while the impact on enantioselectivity was small, the efficiency of diazo compound generation was influenced, and CH3CN and 1,4-dioxane emerged as the optimum solvents. A general rationalization of the factors that influence both relative and absolute stereochemistry for all of the different substrates is provided. Reversibility in formation of the betaine intermediate is an important issue in the control of diastereoselectivity. Hence, where low diastereocontrol was observed, the results have been rationalized in terms of the factors that contribute to the reduced reversion of the syn betaine back to the original starting materials. The enantioselectivity is governed by ylide conformation, facial selectivity in the ylide reaction, and, again, the degree of reversibility in betaine formation. From experimental evidence and calculations, it has been shown that sulfide 7 gives almost complete control of facial selectivity, and, hence, it is the ylide conformation and degree of reversibility that are responsible for the enantioselectivity observed. A simple test has been developed to ascertain whether the reduced enantioselectivity observed in particular cases is due to poor control in ylide conformation or due to partial reversibility in the formation of the betaine.

First enantioselective synthesis of vinyl oxiranes from aldehydes and ylides generated from allyl halides and chiral sulfides

Asymmetric allylidenation of aldehydes with sulfur ylides is possible with proper substitution of the initial sulfide, to avoid the [2,3] sigmatropic rearrangement of the unsaturated ylides. One-pot reaction of (2R,5R)-dimethylthiolane with allyl halides,

Two-step synthesis of trans-2-arylcyclopropane carboxylates with 98-100% ee by the use of a phosphazene base

Only the axial diastereomer of sulfonium salts 2 are formed upon alkylation of 1. Deprotonation of 2 results in ylides, which allow the highly enantioselective cyclopropanation of Michael systems. The chirat auxiliary 1 is recovered and can be reused.

Stereospecific rearrangements of optically active 2-aryl-3-ethenyloxiranes to give optically active β-ethenylbenzeneethanols: Benzyl vs. allyl cations and an efficient synthesis of (s)-ibuprofen

Rearrangements of aryl- and ethenyl-substituted oxiranes proceed well in the presence of triethylsilane and BF3 to give optically active alcohols, which we have used for a synthesis of (S)-ibuprofen 1. We have also shown that a vinyl group migrates to a benzylic cation faster than a phenyl group migrates to an allyl cation.