1474-58-4

Upstream product

• 55105-71-0 3β-chlorocholest-5-en-7-one 
• 80-97-7 3-β-cholestanol 
• 80-97-7 Cholestanol 
• 3381-51-9 (3S,5S,8R,9S,10S,13R,14S,17R)-10,13-dimethyl-17-((R)-6-methylheptan-2-yl)hexadecahydro-1H-cyclopenta[a]phenanthren-3-yl methanesulfonate 
• 481-21-0 cholestane 
• 3381-52-0 3β-(toluene-4-sulfonyloxy)-5α-cholestane 
• 1174658-53-7 C₃₆H₅₃NO₃S 
• 1174658-52-6 C₃₉H₆₂O₇S 
• 80-97-7 (5α)-cholestan-3β-ol 

Downstream Products

• 481-21-0 cholestane 
• 80-97-7 Cholestanol 
• 516-95-0 epicholestanol 
• 13901-19-4 cholest-2-ene 
• 28398-70-1 (20R)-5β,14β-dimethyl-18-19-dinor-8α,9β,10α-cholest-13(17)-ene 
• 28398-71-2 (20S)-5β,14β-dimethyl-18-19-dinor-8α,9β,10α-cholest-13(17)-ene 
• 5847-30-3 3α-chloro-5α-cholestane 
• 4405-84-9 2α-chlorocholestane 
• 1175-09-3 2α,3β-Dibrom-cholestan 
• 1175-10-6 2β,3α-Dibrom-cholestan 
• 17150-07-1 3α-(phenylthio)cholestane 

Relevant academic research and scientific papers

Practical and Selective sp3 C?H Bond Chlorination via Aminium Radicals

The introduction of chlorine atoms into organic molecules is fundamental to the manufacture of industrial chemicals, the elaboration of advanced synthetic intermediates and also the fine-tuning of physicochemical and biological properties of drugs, agrochemicals and polymers. We report here a general and practical photochemical strategy enabling the site-selective chlorination of sp3 C?H bonds. This process exploits the ability of protonated N-chloroamines to serve as aminium radical precursors and also radical chlorinating agents. Upon photochemical initiation, an efficient radical-chain propagation is established allowing the functionalization of a broad range of substrates due to the large number of compatible functionalities. The ability to synergistically maximize both polar and steric effects in the H-atom transfer transition state through appropriate selection of the aminium radical has provided the highest known selectivity in radical sp3 C?H chlorination.

C-HALOGEN BOND FORMATION

Methods of halogenating a carbon containing compound having an sp3 C-H bond are provided. Methods of fluorinating a carbon containing compound comprising halogenation with Cl or Br followed by nucleophilic substitution with F are provided. Methods of direct oxidative C-H fluorination of a carbon containing compound having an sp3 C-H bond are provided. The halogenated products of the methods are provided.

Stereoretentive chlorination of cyclic alcohols catalyzed by titanium(IV) tetrachloride: Evidence for a front side attack mechanism

A mild chlorination reaction of alcohols was developed using the classical thionyl chloride reagent but with added catalytic titanium(IV) chloride. These reactions proceeded rapidly to afford chlorination products in excellent yields and with preference for retention of configuration. Stereoselectivities were high for a variety of chiral cyclic secondary substrates including sterically hindered systems. Chlorosulfites were first generated in situ and converted to alkyl chlorides by the action of titanium tetrachloride which is thought to chelate the chlorosulfite leaving group and deliver the halogen nucleophile from the front face. To better understand this novel reaction pathway, an ab initio study was undertaken at the DFT level of theory using two different computational approaches. This computational evidence suggests that while the reaction proceeds through a carbocation intermediate, this charged species likely retains pyramidal geometry existing as a conformational isomer stabilized through hyperconjugation (hyperconjomers). These carbocations are then essentially "frozen" in their original configurations at the time of nucleophilic capture.

Iron(III)-catalyzed halogenations by substitution of sulfonate esters

A novel halogenation reaction from sulfonates catalyzed by iron(III) is described. The reaction can be performed as a stoichiometric or a catalytic version. This reaction provides a convenient strategy for the efficient access to structurally diverse secondary chlorides, bromides and iodides. The stereochemical course of the reaction is governed by the substrate and the experimental conditions. Secondary alcohols modified as quisylates or pysylates are substantially more reactive. Aliphatic quisylates proceed with overall inversion of configuration under catalytic conditions. Chemoselectivity in bismesylates was observed in favour of the secondary mesylate. Additionally, based on the experimental results, a possible catalytic cycle for the halogenation has been proposed.

Manganese porphyrins catalyze selective C-H bond halogenations

We report a manganese porphyrin mediated aliphatic C-H bond chlorination using sodium hypochlorite as the chlorine source. In the presence of catalytic amounts of phase transfer catalyst and manganese porphyrin Mn(TPP)Cl 1, reaction of sodium hypochlorite with different unactivated alkanes afforded alkyl chlorides as the major products with only trace amounts of oxygenation products. Substrates with strong C-H bonds, such as neopentane (BDE =～100 kcal/mol) can be also chlorinated with moderate yield. Chlorination of a diagnostic substrate, norcarane, afforded rearranged products indicating a long-lived carbon radical intermediate. Moreover, regioselective chlorination was achieved by using a hindered catalyst, Mn(TMP)Cl, 2. Chlorination of trans-decalin with 2 provided 95% selectivity for methylene-chlorinated products as well as a preference for the C2 position. This novel chlorination system was also applied to complex substrates. With 5α-cholestane as the substrate, we observed chlorination only at the C2 and C3 positions in a net 55% yield, corresponding to the least sterically hindered methylene positions in the A-ring. Similarly, chlorination of sclareolide afforded the equatorial C2 chloride in a 42% isolated yield. Regarding the mechanism, reaction of sodium hypochlorite with the MnIII porphyrin is expected to afford a reactive MnVO complex that abstracts a hydrogen atom from the substrate, resulting in a free alkyl radical and a MnIV-OH complex. We suggest that this carbon radical then reacts with a MnIV-OCl species, providing the alkyl chloride and regenerating the reactive MnVO complex. The regioselectivity and the preference for CH2 groups can be attributed to nonbonded interactions between the alkyl groups on the substrates and the aryl groups of the manganese porphyrin. The results are indicative of a bent [MnvO-H-C] geometry due to the C-H approach to the MnvO (dπ-pπ)* frontier orbital.

Clarification of the stereochemical course of nucleophilic substitution of arylsulfonate-based nucleophile assisting leaving groups

(Chemical Equation Presented) Secondary alcohols modified as tosylates, PEG-sulfonates, or quisylates undergo inversion of configuration at the reacting center when treated with lithium halide in acetone at reflux, where the PEG-sulfonates and quisylates are substantially more reactive. In sterically hindered cases, elimination is a competing process. In contrast, when treated with TiCl4, simple secondary sulfonates give chloride products with partial inversion of configuration. Any observed retention of configuration in a given alkyl sulfonate substrate under these conditions is likely due to neighboring group participation or diastereoselective attack on a carbocation (or ion pair) rather than an SNi mechanism.

SYNTHESIS OF ALKYL HALIDES UNDER NEUTRAL CONDITIONS

Primary and secondary alcohols are efficiently converted to the corresponding alkyl halides under neutral conditions.