7712-82-5Relevant academic research and scientific papers
Stereochemical mechanism of two sabinene hydrate synthases forming antipodal monoterpenes in thyme (Thymus vulgaris)
Krause, Sandra T.,Koellner, Tobias G.,Asbach, Julia,Degenhardt, Joerg
, p. 112 - 121 (2013)
The essential oil of Thymus vulgaris consists of a complex blend of mono- and sesquiterpenes that provides the plant with its characteristic aromatic odor. Several chemotypes have been described for thyme. In this study, we identified two enzymes of the sabinene hydrate chemotype which are responsible for the biosynthesis of its major monoterpene alcohols, (1S,2R,4S)-(Z)-sabinene hydrate and (1S,2S,4R)-(E)-sabinene hydrate. Both TPS6 and TPS7 are multiproduct enzymes that formed 16 monoterpenes and thus cover almost the whole monoterpene spectrum of the chemotype. Although the product spectra of both enzymes are similar, they form opposing enantiomers of their chiral products. Incubation of the enzymes with the potential reaction intermediates revealed that the stereospecificity of TPS6 and TPS7 is determined by the formation of the first intermediate, linalyl diphosphate. Since TPS6 and TPS7 shared an amino acid sequence identity of 85%, a mutagenesis study was employed to identify the amino acids that determine the stereoselectivity. One amino acid position had a major influence on the stereochemistry of the formed products. Based on comparative models of TPS6 and TPS7 protein structures with the GPP substrate docked in the active site pocket, the influence of this amino acid residue on the reaction mechanism is discussed.
Cyclopropanation with dibromomethane under grignard and barbier conditions
Brunner, Gerhard,Eberhard, Laura,Oetiker, Juerg,Schroeder, Fridtjof
scheme or table, p. 3708 - 3718 (2010/04/02)
Tertiary Grignard reagents and dibromomethane efficiently cyclopropanate allylic (and certain homoallylic) magnesium and lithium alcoholates at ambient temperature in ether solvents. Lithium (homo)allyl alcoholates are directly cyclopropanated with magnes
Tandem cyclopropanation with dibromomethane under Grignard conditions
Brunner, Gerhard,Eberhard, Laura,Oetiker, Juerg,Schroeder, Fridtjof
, p. 7543 - 7554 (2008/12/22)
(Chemical Equation Presented) Tertiary Grignard reagents and dibromomethane efficiently cyclopropanate allylic (and certain homoallylic) magnesium and lithium alcoholates at ambient temperature in ether solvents. Lithium (homo)allyl alcoholates are directly cyclopropanated with magnesium and CH 2Br2 under Barbier conditions at higher temperatures. The reaction rates depend on the substitution pattern of the (homo)allylic alcoholates and on the counterion with lithium giving best results. Good to excellent syn-selectivities are obtained from α-substituted substrates, which are in accord with a staggered Houk model. In tandem reactions, cyclopropyl carbinols are obtained from allyloxylithium or -magnesium intermediates, generated in situ by alkylation of conjugated aldehydes, ketones, and esters as well as from allyl carboxylates or vinyloxiranes. Using this methodology, numerous fragrance ingredients and their precursors were efficiently converted to the corresponding cyclopropyl carbinols.
A short and efficient synthesis of (±)-trans-sabinene hydrate
Galopin, Christophe C.
, p. 5589 - 5591 (2007/10/03)
A short synthesis of sabinene hydrate is reported. It uses cheap starting materials and affordable reagents. The main product of the synthesis is trans-sabinene hydrate.
Allylic Lithium Oxyanionic Directed and Facilitated Simmons-Smith Cyclopropanation: Stereoselective Synthesis of (±)-cis-Sabinene Hydrate and a Novel Ring Expansion
Cheng, Dai,Kreethadumrongdat, Thanapong,Cohen, Theodore
, p. 2121 - 2123 (2007/10/03)
(matrix presented) The lithium salts of acid-sensitive allyl alcohols, which themselves decompose during Simmons-Smith cyclopropanation, undergo smooth cyclopropanation in the usual stereocontrolled manner. This concept is applied to the most efficient synthesis of (±)-cis-sabinene hydrate and to the cyclopropanation of the anion of a nonisolable allyl alcohol resulting upon workup in a ring-expanded enone. The cyclopropanations are also faster for the lithium salts than for the allyl alcohols themselves.
