26828-76-2

Upstream product

• 32591-15-4 trans-5-tert-butylcyclohex-2-enol 
• 17502-34-0 cis-5-tert-butylcyclohex-2-en-1-ol 
• 17502-34-0 trans-5-tert-butyl-2-cyclohexenol 

Downstream Products

• 99417-68-2 (1R,2R,3R,5R)-5-tert-Butyl-3-phenylselanyl-cyclohexane-1,2-diol 
• 99417-67-1 (1S,2R,3R,5S)-5-tert-Butyl-2-phenylselanyl-cyclohexane-1,3-diol 
• 58519-76-9 2-trans-Azido-5-trans-tert.-butylcyclohexan-1r,3-cis-diol 
• 99417-64-8 (4S,6S)-4-tert-Butyl-6-hydroxy-cyclohex-2-enone 
• 99417-61-5 (1S,2R,5S)-5-tert-Butyl-cyclohex-3-ene-1,2-diol 
• 99417-72-8 (4R,6S)-4-tert-Butyl-3-methyl-6-trimethylsilanyloxy-cyclohex-2-enone 

Relevant academic research and scientific papers

A highly chemoselective, diastereoselective, and regioselective epoxidation of chiral allylic alcohols with hydrogen peroxide, catalyzed by sandwich-type polyoxometalates: Enhancement of reactivity and control of selectivity by the hydroxy group through metal-alcoholate bonding

Sandwich-type polyoxometalates (POMs), namely [VZnM2(ZnW9O34)2]q- [M = Mn(II), Ru(III), Fe(III), Pd(II), Pt(II), Zn(II); q = 10-12], are shown to catalyze selectively the epoxidation of chiral allylic alcohols with 30% hydrogen peroxide under mild conditions (ca. 20 °C) in an aqueous/organic biphasic system. The transition metals M in the central ring of polyoxometalate do not affect the reactivity, chemoselectivity, or stereoselectivity of the allylic alcohol epoxidation by hydrogen peroxide. Similar selectivities, albeit in significantly lower product yields, are observed for the lacunary Keggin POM [PW11O39]7-, in which a peroxotungstate complex has been shown to be the active oxidizing species. All these features support a tungsten peroxo complex rather than a high-valent transition-metal oxo species operates as the key intermediate in the sandwich-type POM-catalyzed epoxidations. On capping of the hydroxy functionality through acetylation or methylation, no reactivity of these hydroxy-protected substrates [1a(Ac) and 1a(Me)] is observed by these POMs. A template is proposed to account for the marked enhancement of reactivity and selectivity, in which the allylic alcohol is ligated through metal - alcoholate bonding, and the H2O2 oxygen source is activated in the form of a peroxotungsten complex. 1,3-Allylic strain promotes a high preference for the threo diastereomer and 1,2-allylic strain a high preference for the erythro diastereomer, whereas tungsten - alcoholate bonding furnishes high regioselectivity for the epoxidation of the allylic double bond. The estimated dihedral angle α of 50 - 70° for the metal - alcoholate-bonded template of the POM/H2O2 system provides the best compromise between 1,2A and 1,3A strain during the oxygen transfer. In contrast to acyclic allylic alcohols 1, the M-POM-catalyzed oxidation of the cyclic allylic alcohols 4 by H2O2 gives significant amounts of enone.

Allylic CH oxidation versus epoxidation of 2-cyclohexenols, catalyzed by chromium- and manganese-substituted polyoxometalates and salen complexes

2-Cyclohexenol (1) is oxidized chemoselectively to 2-cyclohexenone (2a) by the α-Keggin chromium-substituted polyoxometalate (POM) Ia as the catalyst and iodosobenzene as the oxygen source. For the chromium(salen) catalyst IIa the same chemoselectivity in favor of allylic CH oxidation is observed. The manganese-substituted POM Ib and the manganese(salen) complex IIb, however, afford appreciable amounts of the epoxy alcohol 2b. For the stereolabeled 5-tert-butyl-2-cyclohexenols 5, the diastereoselectivity of the epoxidation was appreciable (syn:anti 82:18) in the case of the manganese (salen) complex IIb with the cis isomer, while the manganese-substituted POM Ib exhibited no syn versus anti π-facial differentiation for the cis or trans diastereomer of the cyclohexenol 5. The observed syn hydroxy directivity for the manganese(salen) complex IIb is rationalized in terms of optimal hydrogen bonding between the MnV oxo complex IIb and the trans diastereomer of the allylic alcohol substrate 5. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany 2002.

Steric and electronic effects in the diastereoselective catalytic epoxidation of cyclic allylic alcohols with methyltrioxorhenium (MTO)

The steric effects of allylic substituents in the epoxidations with methyltrioxorhenium/urea/hydrogen peroxide adduct (MTO/UHP) have been assessed for a series of 3-alkyl-substituted cyclohexenes. The trans selectivity increases with the size of the substituent and the diastereoselectivities follow an excellent linear correlation with the steric substituent constants of Taft (E(s)) or Charton (v). Good cis selectivity is observed in the epoxidation of the cyclic allylic alcohols 2-cyclopentenol and 2-cyclohexenol due to a hydroxy-directing effect through hydrogen bonding; however, for 2-cycloheptenol and 2-cyclooctenol hydrogen bonding is ineffective and steric interactions cause a higher trans selectivity. The conformationally fixed cis- and trans-5-tert-butyl-2-cyclohexenols serve as suitable substrates for gauging the dihedral angle of the transition states for the oxygen transfer in these epoxidations. Thus, the MTO/UHP oxidant favours a quasi-equatorial arrangement of the hydroxy group for effective hydrogen bonding (hydroxy-group directivity), in analogy to m- chloroperbenzoic acid (m-CPBA) and dimethyldioxirane (DMD), and a dihedral angle of ca. 130°is suggested.

Solvent Effects in the Dimethyldioxirane Oxidation of Allylic Alcohols: Evidence for Hydrogen Bonding in the Dipolar Transition State of Oxygen Transfer

A notably higher diastereoselectivity is observed in the dimethyldioxirane epoxidation of chiral allylic alcohols when less polar solvent mixtures are employed; this is interpreted in terms of a dipolar transition state with OH association through hydrogen bonding to the dioxirane, for which a preferential dihedral angle of >130 deg is estimated.

STEREOSELECTIVE EPOXIDATION OF ALLYLIC AND HOMOALLYLIC ALCOHOLS WITH 30percent HYDROGEN PEROXIDE CATALYZED BY TUNGSTIC ACID IN BUFFERED MEDIA

The aqueous tungstic acid-catalyzed hydrogen peroxide epoxidation of allylic alcohols affords the same major diastereoisomer as the VO(acac)2/tBuOOH system with quite comparable stereoselectivities.In contrast, epoxidation of homoallylic alcohols appears to be much less stereoselective.