117516-41-3

Upstream product

• 123-73-9 trans-Crotonaldehyde 
• 557-20-0 diethylzinc 
• 4798-58-7 (E)-hex-4-en-3-ol 
• 123-73-9 crotonaldehyde 
• 765915-07-9 (R,E)-hex-4-en-3-yl acetate 
• 57031-79-5 trans-hex-4-en-3-yl acetate 
• 50396-96-8 E-4-hexen-3-one 
• 108-24-7 acetic anhydride 
• 108-05-4 vinyl acetate 

Downstream Products

• 765915-08-0 (3R,E)-3-[2-(diphenylphosphanyl)benzoyloxy]-4-hexene 
• 765915-06-8 (3S,E)-3-[2-(diphenylphosphanyl)benzoyloxy]-4-hexene 
• 1228041-07-3 C₁₄H₁₉NO₄S 
• 765915-15-9 (2S,4S,6R)-trimethyl-1-(4'-methoxybenzyloxy)-dec-(7E)-ene 
• 765915-11-5 (2S,4R)-dimethyl-1-(4'-methoxybenzyloxy)-oct-(5E)-ene 
• 765915-10-4 (2S,4S)-dimethyl-1-(4'-methoxybenzyloxy)-oct-(5E)-ene 
• 765915-16-0 1-((2S,4R)-2,4-Dimethyl-octyloxymethyl)-4-methoxy-benzene 

Relevant academic research and scientific papers

Chiral ions in the gas phase. 1. Intramolecular racemization and isomerization of O-protonated (S)-trans-4-hexen-3-ol

The acid-catalyzed racemization and regioisomerization of (S)-trans-4- hexen-3-ol (1S) has been investigated in gaseous CH4 and C3H8 at 720 Torr and in the 40-120 °C temperature range. The contribution to the racemization and isomerization products by free 1-methyl-3-ethylallyl cations, arising from unimolecular fragmentation of excited O-protonated (S)-trans-4-hexen-3- ol (IS), was evaluated by generating them from protonation of isomeric 2,4- hexadienes and by investigating their behavior toward H218O under the same experimental conditions. The rate constant of the gas phase racemization of IS (1.4-21.3 x 106 s-1) was found to exceed that of its isomerization (1.0-9.9 x 106 s-1) over the entire temperature range. The experimental results, combined with ab initio theoretical calculations on the model [C3H5+/H2O] system, are consistent with a gas phase intramolecular 1S racemization and isomerization involving the intermediacy of structured ion- molecule complexes, wherein the H20 molecule is coplanarly coordinated to the hydrogen atoms of the 1-methyl-3-ethylallyl moiety. The rate of formation of these structured complexes, their relative stability, and the dynamics of their evolution to the racemized and isomerized products depend, in the gas phase, on the specific conformation of IS. The relevant activation parameters point to transition structures wherein a substantial fraction of the positive charge is located on the allyl moiety. The results obtained in the present gas phase investigation confirm previous indications about the occurrence and the role of intimate ion-molecule pairs in acid-catalyzed racemization and isomerization of optically active alcohols, including allylic alcohols, in solution.

Preparation of stereodefined homoallylic amines from the reductive cross-coupling of allylic alcohols with imines

Regio-, diastereo-, and enantioselective coupling reactions between imines and allylic alcohols have been developed. These coupling reactions deliver complex homoallylic amine products through a convergent C-C bond forming process that does not proceed through intermediate allylic organometallic reagents. In general, convergent coupling, by exposure of an allylic alkoxide to a preformed Ti-imine complex, occurs with allylic transposition in a predictable and stereocontrolled manner. While simple diastereoselection in these reactions is high, delivering anti-products with ≥20:1 selectivity, the organometallic transformation described is compatible with a diverse range of functionality and substrates (including aliphatic and aromatic imines, allylic silanes, trisubstituted alkenes, vinyl- and aryl halides, trifluoromethyl groups, thioethers, and aromatic heterocycles). Alkene geometry of the products is a complex function of the allylic alcohol structure and is consistent with a mechanistic proposal based on syn-carbometalation followed by syn-elimination by way of a boat-like transition state geometry. Single asymmetric coupling reactions provide a means to translate the stereochemical information of the allylic alcohol to the homoallylic amine or to control diastereoselection in the coupling reactions of achiral allylic alcohols with chiral imines. Double asymmetric coupling reactions are also described that afford a unique means to control stereoselection in these complex convergent coupling processes. Finally, empirical models are proposed that are consistent with the observed stereochemical course of these coupling reactions en route to chiral homoallylic amines possessing di- or trisubstituted alkenes and anti- or syn- relative stereochemistry at the allylic and homoallylic positions.

Gold(I)-catalyzed highly regio- and stereoselective decarboxylative amination of allylic N-tosylcarbamates via base-induced aza-Claisen rearrangement in water

(Figure Presented)A gold(l)-catalyzed decarboxylative animation of allylic N-tosylcarbamates via base-induced aza-Claisen rearrangement has been developed. A variety of substituted W-tosyl allylic amines were obtained In good yield, excellent regloselectlvity, and high to excellent stereoselectivity. This transformation could be performed either in H2O or In one pot directly from allylic alcohols and therefore represents an efficient and environmentally benign protocol for the synthesis of N-tosyl allylic amines.

Iterative deoxypropionate synthesis based on a copper-mediated directed allylic substitution: Formal total synthesis of borrelidin (C3-C11 fragment)

A new iterative strategy for the flexible preparation of any oligodeoxypropionate stereoisomer is presented which relies on an o-DPPB-directed copper mediated allylic substitution employing enantiomerically pure Grignard reagents; the reaction is working with perfect control over all aspects of the reaction selectivity. This key C-C bond-forming step features reversed polarity compared with established enolate alkylation methodology. It thus avoids existing problems of enolate alkylation strategies such as enolate reactivity as well as costs and problems associated with the chiral auxiliary. Practicability of this new method is demonstrated through application in natural product syntheses. Thus, an efficient synthesis of the northern part of the angiogenesis inhibitor borrelidin (28), the deoxypropionate building block 27, could be devised, representing a formal total synthesis.

Iterative deoxypropionate synthesis based on a copper-mediated directed allylic substitution

Can't have too much of a good thing: A flexible, iterative strategy based on a highly selective copper-mediated allylic substitution makes the preparation of any desired oligo(deoxypropionate) stereoisomer possible (see scheme; RDG = reagent-directing group). This approach differs from the established enolate-alkylation methodology through the reversed polarity of the reaction partners and avoids several problems associated with the latter method.

A convenient synthesis of piperidine-based β-amino alcohols from L-Phe and highly enantioselective addition of diethyl zinc to aldehydes

β-Amino alcohols 4a-e were easily prepared from L-phenylalanine in three simple straightforward steps. The key intermediate compound (S)-3 was achieved in high yield (up to 92%) with glutaraldehyde and NaBH4/H2SO4 in THF at room temperature. These five ligands were applied to catalyze enantioselective addition of diethyl zinc to aldehydes, high asymmetric induction was observed with 4c and 4e, and the ee value was up to 98%. The effect of the substitutes on the nitrogen atom was also observed via comparing piperidine-based amino alcohols with pyrrolidine-based similar ligands.

Engineering catalysts for enantioselective addition of diethylzinc to aldehydes with racemic amino alcohols: Nonlinear effects in asymmetric deactivation of racemic catalysts

Correct additions make a difference: Asymmetric deactivation and asymmetric amplification concepts coupled with a high-throughput screening technique provided a successful strategy for designing a highly enantioselective catalytic system by simple combination of a racemic amino alcohol (rac-DB) and a nonracemic additive (AA). The example in the scheme shows the conversion of 1 into 2 with up to 92.7% ee.

From Highly Enantioselective Monomeric Catalysts to Highly Enantioselective Polymeric Catalysts: Application of Rigid and Sterically Regular Chiral Binaphthyl Polymers to the Asymmetric Synthesis of Chiral Secondary Alcohols

A 1,1′-binaphthyl-based polymeric chiral catalyst with the most general enantioselectivity for the alkylzinc addition to a broad range of aldehydes has been obtained. This polymer can be easily recovered, and the recycled polymer shows the same catalytic properties as the original polymer. A highly enantioselective catalytic diphenylzinc addition to aldehydes has also been achieved by using the chiral binaphthyl monomer and polymer catalysts. Particularly, the excellent enantioselectivity observed for the addition of diphenylzinc to aromatic aldehydes allows the preparation of optically active diaryl carbinols that are synthetically useful but difficult to access by asymmetric catalysis. A novel asymmetric reduction of ketones catalyzed by the mono- and polybinaphthyl zinc complexes has been discovered. Our work on the asymmetric organozinc addition to aldehydes and the asymmetric reduction of ketones catalyzed by the zinc complexes of chiral binaphthyl monomer (R)-12 and polybinaphthyl (R)-43 has not only provided new methods to prepare optically active secondary alcohols but also demonstrated that incorporation of an enantioselective monomeric catalyst into a rigid and sterically regular polymer structure could almost completely preserve the catalytic properties of the monomeric catalyst. This strategy may find general application in converting existing highly enantioselective monomer catalysts into polymer catalysts of similar enantioselectivity provided that the catalytically active species of the monomer catalysts contain only the monomeric units rather than the aggregates of the monomers. By using this strategy, it is possible to overcome the drawbacks associated with the traditional approach to preparing polymeric chiral catalysts where the microenvironments of the catalytic sites in the polymers are often significantly altered from those in the monomeric catalysts due to the flexible and sterically irregular polymer chains.

Synthesis of unit A of cryptophycin via a [2,3]-Wittig rearrangement

The synthesis of unit A of the cryptophycins from (S)-trans-3-penten-2- ol and from (S)-trans-4-hexen-3-ol has been completed. The key stereodetermining step is a [2,3]-Wittig rearrangement of a propargyl ether. Elaboration of the rearrangement product was accomplished by means of a selective hydroboration-oxidation of a terminal alkyne, Horner-Emmons homologation of the derived aldehyde, followed by selective ozonolytic cleavage and Wittig olefination. This synthesis provides easy access to the series of cryptophycin analogues that incorporate a modified aromatic ring in unit A.

Synthesis of (R)-( - )-1-piperidino-3,3-dimethylbutan-2-ol: Application in the molar scale asymmetric ethylation of trans-crotonaldehyde

A simple three-step preparation of (R)-( - )-1-piperidino-3,3-dimethylbutan-2-ol (amino alcohol catalyst for the Noyori asymmetric alkylation of aldehydes) based on a classical resolution of the racemate is described. Use of this catalyst in a detailed study of the asymmetric ethylation of trans-crotonaldehyde producing trans-(S)-4-hexen-3-ol is also described. The impact of catalyst enantiopurity and loading on the product enantiopurity and yield is studied, which led to optimized conditions for reaction scale-up.