Organic Chemistry A

Goals
- improve the knowledge on the structure of organic molecules and of reaction mechanisms
- provide concepts about reactions of great interest in organic synthesis, that are not discussed in basic organic chemistry courses,
- improve experimental lab's techniques and practical skills aimed to make the synthetic work independently


acquired skills
The student will acquire skills complementary to those already attained in the field of stereochemistry, in advanced organic synthesis and specific reactions mechanisms and pericyclic reactions.
From the laboratory training he will gain expertise in the execution and work up of sophisticated organic reactions performed under inert atmosphere and with stereochemical aspects.



Course content

Lessons prof. Licandro (6 credits)
Stereochemistry. Configuration. Symmetry and chirality. Stereogenic units. Stereogenic centers. Configuration at tetrahedral atoms. Configuration at double bonds. Configuration at cyclic systems. Prochiral centers. Topism. Molecules with multiple stereogenic centers. Chirality and optical activity. Diastereotopic and enantiotopic atoms, groups or faces. Absolute Configuration. Analysis and separation of enantiomeric mixtures. Conformation. Conformational analysis. Conformation in open-chain systems. Conformation in six-membered rings. Conformation in heteroatom containing six-membered rings. Conformation in other rings. Stereoselectivity. Stereoselective and stereospecific syntheses. Enantioselective syntheses. Conformational, torsional and stereoelectronic effects on reactivity. Double stereo-differentiation.
Reaction Mechanisms -Types of mechanism (heterolytic, homolytic, pericyclic). Types of reactions (substitution, addition to double or triple bonds, -elimination, rearrangement). Reaction intermediates (ionic, radical, organometallic). Methods of determining reaction mechanisms (determination of the presence of an intermediate, isotopic labelling, stereochemical evidence, the study of catalysis, isotope effects, kinetic evidence). Stepwise reactions and intermediate formation.
Carbocations (structure and stability; generation and reactivity of carbocations, non- classical carbocations). SN1 Mechanism. Addition to carbon-carbon multiple bonds (alkenes, dienes, allyl/vinyl silanes and allyl/vinyl stannanes). E1 Mechanism.
Free radicals (structure and stability, generation and reactivity of radicals). Radical addition to double bonds. Radical cyclizations. Reactions at unactivated C-H bonds.
One-step mechanism, without intermediate formation. SN2 and E2 mechanism.
Pericyclic reactions. Concerted cycloadditions. The perturbational Theory. The Diels-Alder reaction (Regioselectivity and stereochemistry. Substituent effects. Lewis acid catalysis. Diastereoselective Diels-Alder reactions using chiral auxiliaries. Enantioselective catalysis in Diels-Alder reaction. Intramolecular Diels-Alder reactions. Scope and synthetic applications. 1,3-Dipolar Cycloadditions (Regiochemistry and stereochemistry. Catalysis. Scope and applications). [2+2]-Cycloadditions (Cycloaddition reactions of alkenes and ketenes. Synthesis of Cyclobutanes). Unimolecular rearrangements.[1,j]- Sigmatropic rearrangements. [3,3]-Sigmatropic rearrangements (Cope and modified Cope rearrangements. Claisen and modified Claisen rearrangements). [2,3]-Sigmatropic rearrangements (rearrangement of allylic sulfoxides, amine oxides, allylic sulfonium and ammonium ylides). Wittig and aza-Wittig rearrangements.
Unimolecular thermal eliminations (cheletropic reactions, decomposition of cyclic azo-compounds, -eliminations via cyclic transition states).

Lessons and laboratory prof. Bernardi (3 cfu)
Some of the reactions discussed in the course will be performed in the laboratory, focusing on inert atmosphere working and other advanced techniques. Stereochemical aspects of the reactions will also be considered.

Suggested prerequisites
Bachelor level Organic Chemistry courses

Reference material
(1) F. A. Carey, R. J. Sundberg, Advanced Organic Chemistry, Part B: Reactions and Synthesis, V Edition, 2007 Springer Science;
(2) F. A. Carey, R. J. Sundberg, Advanced Organic Chemistry, Part A: Structure and Mechanisms, V Edition, 2007 Springer Science.

Assessment method
Organic chemistry module: students are evaluated through a written examination. In the case of not-fully positive evaluation of the written examination, at teacher' s discretion, students will also undergo a colloquium done in the same exam session. Both written exam and colloquium concern the whole program of the course.
Laboratory module: students are evaluated on the basis of the knowledge and the skill acquired performing the experiments.
The final course-grade is a weighted average of the two modules evaluations.

Language of instruction
English

Attendance Policy
Lessons prof. Licandro: it is strongly recommended that students attend class regularly from the beginning of the term and meet all requirements set by the instructor.
Lessons and laboratory prof. Bernardi: attendance at all scheduled laboratory lessons and experiments is compulsory.

Mode of teaching
Teacher-centered, interactive lessons, accompanied by power-point presentations