A synthetic receptor for hydrogen-bonding to fluorines of trifluoroborates.

A tripodal receptor featuring three inwardly-directed hydrogen-bond donors binds covalently bound fluorine atoms of trifluoroborates through hydrogen-bonding.

Pseudo-capsule assemblies characterized by 19F NMR techniques.

The formation of capsule-like dynamic assemblies which do not rely on attractions between host subunits was achieved via specific interactions with fluorinated guests. Characterization of these three component assemblies was accomplished by applications of (19)F NMR spectroscopy.

A cavitand with a fluorous rim acts as an amine receptor.

A deep cavitand featuring eight trifluoroacetyl groups attached to the open end has been synthesized; these functions provide new chemical surfaces and constrict access to the cavitand, yet increase the rates of guest exchange.

Reaction of isonitriles with carboxylic acids in a cavitand: observation of elusive isoimide intermediates.

A deep cavitand with an inwardly directed carboxylic acid function reacts with small aliphatic isonitriles to form N-acyl formamides inside the cavity. The unique isolation and stabilization of covalently bound guests within the structured environment of the cavitand allows for observation of the labile O-acyl isoimide intermediate using conventional spectroscopic methods.

Synthesis of alpha-helix mimetics with four side-chains.

The synthesis of a heterocyclic piperazine-based scaffold that mimics the i, i+4, i+8, i+11 side-chain projections of an alpha-helix is described. The synthesis is designed to be modular to allow the targeting of a range of protein-protein interactions involving alpha-helices.

Total Synthesis of +-alexine by utilizing a highly stereoselective [3+2] annulation reaction of an N-tosyl-alpha-amino aldehyde and a 1,3-bis(silyl)propene.

A novel route towards the polyhydroxylated pyrrolizidine alkaloid (+)-alexine has been developed. A key step in this synthesis is a highly stereoselective [3+2] annulation reaction of N-Ts-alpha-amino aldehyde 7 a (Ts=tosyl) and 1,3-bis(silyl)propene 8 a for the construction of the polyhydroxylated pyrrolidine subunit of the target molecule. Previous synthetic strategies rely on carbohydrates that require several protecting-group manipulations, thereby making the total number of steps relatively high.

Cavitands with introverted functionality stabilize tetrahedral intermediates.

The synthesis and characterization of two deepened cavitand hosts with introverted functionality--functional groups directed into the cavity--is described. Two functions can be introverted, alcohol and aldehyde, and they show the formation of hemiacetals and hemiketals on binding small guests with complementary functional groups. The structures of the bound hemiacetals are determined by 1D and 2D NMR studies.

Stereoselective synthesis of functionalized pyrrolidines via a [3 + 2]-annulation of N-Ts-alpha-amino aldehydes and 1,3-Bis(silyl)propenes.

An efficient protocol for stereoselective synthesis of densely functionalized pyrrolidines by a [3 + 2]-annulation of N-Ts-alpha-amino aldehydes and 1,3-bis(silyl)propenes is described.

Diastereoselective aldol additions to alpha-amino-beta-silyloxy aldehydes. Divergent synthesis of aminodiols.

A divergent protocol for substrate-controlled diastereoselective synthesis of aminodiols has been developed using nucleophilic Mukaiyama aldol additions to alpha-amino-beta-silyloxy aldehydes. The merged stereochemical impact on the diastereoselectivity of the polar alpha- and beta-substituents is highlighted. [reaction: see text]

Regioselective and divergent opening of vinyl epoxides with ethoxyacetylene.

A divergent protocol for nucleophilic opening of vinyl epoxides with ethoxyacetylide has been developed and demonstrated to give complete regioselectivity depending on reaction conditions.