Biocatalytic single-step alkene cleavage from aryl alkenes: an enzymatic equivalent to reductive ozonization

In ozonolysis, ozone is used to cleave a carbon–carbon double bond to form aldehydes and ketones, or carboxylic acids, depending on the work-up.
Ozone is a symmetrical bent molecule stabilized by a resonance structure.

Alkynes undergo oxidative cleavage in the presence of oxidizing reagents like potassium permanganate and ozone. The triple bond — one σ bond and two π bonds — is completely cleaved, and the alkyne is oxidized to carboxylic acids. When warm and basic aqueous potassium permanganate is used as an oxidizing agent, alkynes are first converted to carboxylate salts via an unstable α-diketone intermediate. Further, a mild acid treatment protonates the carboxylate anions generating free carboxylic acid...

In addition to the oxymercuration–demercuration method, which converts the alkenes to alcohols with Markovnikov orientation, a complementary hydroboration-oxidation method yields the anti-Markovnikov product. The hydroboration reaction, discovered in 1959 by H.C. Brown, involves the addition of a B–H bond of borane to an alkene giving an organoborane intermediate. The oxidation of this intermediate with basic hydrogen peroxide forms an alcohol.

Oxymercuration–reduction of alkenes is one of the major reactions converting alkenes to alcohols. It involves the hydration of alkenes with mercuric acetate in a mixture of tetrahydrofuran and water, forming an organomercury adduct. This is followed by a demercuration step in which the adduct is reduced to an alcohol using sodium borohydride.

Introduction
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.

Catalytic hydrogenation of alkenes is a transition-metal catalyzed reduction of the double bond using molecular hydrogen to give alkanes. The mode of hydrogen addition follows syn stereochemistry.
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...