Thermodynamic and Kinetic Controlled Enolates: A Project for a Problem-Oriented Laboratory Course

A project‐based biochemistry laboratory promoting the understanding and uses of fluorescence spectroscopy in the study of biomolecular structures and interactions

“…If understanding is enhanced by providing a “need‐to‐know” environment, then continual integration of fluorescence theory into course and application into laboratory would provide maximal opportunity for students to learn the science and utility of fluorescence. Previous methods to achieve integration of content or methodology in course and laboratory have ranged from project‐based laboratories based on specific techniques/instrumentation [2–5], specific molecules/molecular systems [6–9], or the development of entirely new project‐based biochemistry laboratory courses [10, 11]. Many articles have been published concerning the use of fluorescence spectroscopy in undergraduate laboratories to study specific biomolecules [12–18], but none have addressed the concept of applying the technique more broadly to complement the course and its themes in general.…”

Novel lupane triterpenoids containing allyl substituents in ring A: synthesis and in vitro study of antiinflammatory and cytotoxic properties

“…It is known 9-11 that effective intermediates in α alkyla tion of ketones are potassium enoxy(triethyl)borates gen erated in situ by reactions of cyclic or acyclic ketones with the reagents KH-Et 3 B, 12 KN(SiMe 3 ) 2 -Et 3 B, 12 and Bu t OK-Et 3 B 13 in ethers. In most cases, the use of such enolate anions allows the regio and stereochemical con trol of reactions and precludes the formation of O alkyla tion, dialkylation, and polyalkylation by products.…”

“…In most cases, the use of such enolate anions allows the regio and stereochemical con trol of reactions and precludes the formation of O alkyla tion, dialkylation, and polyalkylation by products. [12][13][14][15] We found that a reaction of allyl bromide with enolate anion A (generated by treatment of methyl betulonate 1 with KN(SiMe 3 ) 2 in 1,2 dimethoxyethane (DME) fol lowed by addition of Et 3 B (the molar ratio 1 : KN(SiMe 3 ) 2 : : Et 3 B : C 3 H 5 Br was 1 : 1.3 : 1.3 : 1.3) gives shortly (4 h) methyl 2β propenyl 3 oxolup 20(29) en 28 oate (2) as the sole reaction product in 65% yield (Scheme 1). Exten sion of the reaction time to 24 h resulted in the formation of minor 2α propenyl epimer 3 (2β : 2α = 96 : 4, 1 H and 13 C NMR data).…”

Regioselective Synthesis of 6-Chlorofulvene and 6-Aminofulvene via Keto–Enol Tautomerism

“…2−11 However, few regioselective synthesis experiments based on keto−enol tautomerism have been designed to illustrate the shift of keto− enol equilibria. 12 As an illustration, amines as the nucleophile can undergo substitutions with alkyl halides or conjugate addition with α,β-unsaturated aldehydes or ketones to construct C−N bonds. 13−20 In the replacement reactions of vinyl halides with large conjugated system, students are easily getting confused about the mechanism via direct substitution or conjugate addition and then elimination.…”

“…Keto–enol tautomerism refers to a chemical equilibrium between a keto form and an enol form by transfer of a hydrogen atom within the molecule . In the undergraduate laboratory, NMR spectroscopy is usually used to learn tautomerism, which can help students understand the factors that affect keto–enol equilibria, such as aromatic conjugation, steric bulk, electron-withdrawing groups, etc. − However, few regioselective synthesis experiments based on keto–enol tautomerism have been designed to illustrate the shift of keto–enol equilibria . As an illustration, amines as the nucleophile can undergo substitutions with alkyl halides or conjugate addition with α,β-unsaturated aldehydes or ketones to construct C–N bonds. − In the replacement reactions of vinyl halides with large conjugated system, students are easily getting confused about the mechanism via direct substitution or conjugate addition and then elimination.…”