Agenesis of maxillary lateral incisors: Bone formation by orthodontic tooth movement and long-term stability of the edentulous alveolar ridge at 12-15 years after treatment.

Introduction: The primary aim of this study was to assess the amount and long-term stability of orthodontically created bone in patients with agenesis of maxillary lateral incisors after canine distalization. The secondary aim was to explore the impact of patient age on the process of alveolar bone resorption.

Methods: A group of patients with agenesis of the maxillary permanent lateral incisor was examined at 4 time points: the beginning of orthodontic treatment (T1, n = 80), the end of treatment (T2, n = 80), 2-5 years after treatment (T3, n = 79), and 12-15 years after treatment (T4, n = 32).

Stereoselective Synthesis of 1,n-Dicarbonyl Compounds Through Palladium-Catalyzed Ring Opening/Isomerization of Densely Substituted Cyclopropanols.

We report a highly diastereoselective protocol for the synthesis of 1,4- and 1,5-dicarbonyl compounds from densely substituted cyclopropanols. The methodology involves a palladium-catalyzed ring opening reaction followed by a "metal-walk" and oxidation of a remote hydroxyl group. The methodology represents a new application of cyclopropanols as initiation sites for chain walking remote functionalization.

Copper-Catalyzed Carbomagnesiation of 1-Halocyclopropenes.

We report a versatile copper-catalyzed carbomagnesiation reaction of poly- and fully substituted 1-halocyclopropenyl esters. By fine-tuning the regioselectivity of the addition, we were able to access configurationally stable fully substituted cyclopropyl carbenoid intermediates. These intermediates were subsequently trapped with electrophiles to furnish stereodefined poly- and fully substituted halocyclopropyl esters.

Stereoinvertive S1 Through Neighboring Group Participation.

Neighboring group participation, the assistance of non-conjugated electrons to a reaction center, is a fundamental phenomenon in chemistry. In the framework of nucleophilic substitution reactions, neighboring group participation is known to cause rate acceleration, first order kinetics (S1), and retention of configuration. The latter phenomenon is a result of double inversion: the first one when the neighboring group displaces the leaving group, and the second when a nucleophile substitutes the neighboring group.