Abstract: A rod for a construction set includes an elongate strut that extends between opposed of interconnected joint elements. A cavity in each end of the strut slidably supports a clip having opposed inwardly deflectable fingers, with outwardly facing catches at their extremities, that snap fit into the joint openings in the joint element to clamp the joint element between the catches and the ends of the rods. The clips are moveable between closed positions where the fingers are engaged in the joint elements and open positions where the fingers are located completely within the cavity to allow the rod to be removed from opposed joint elements in a structure without disturbing the structure. The struts have slots in their extremities that intersect the cavities, and the fingers have protrusions that extend through the slots to facilitate deflecting the fingers inwardly to release the clips from the joint elements and in moving the clips between their open and closed positions.

Abstract: The present invention relates to a method of forming a 1,3-diamino-3-substituted-2-propanol chemical intermediate from which various chemicals, such as selected protease-inhibitors and other drugs, as well as polymers, can be synthesized.This method includes contacting a nitromethyl amino acid compound with at least one reducing agent to form the 1,3-diamino-3-substituted-2-propanol chemical intermediate.

Abstract: This invention provides a simplified method for converting pregnan-3,20-dione compounds to 3.alpha.-hydroxy,3.beta.-substituted-pregnanes. By selective use of reagents the unprotected dione is converted chemoselectively and diastereoselectively into a 3(R)-pregnan-3-spiro-2'oxirane-20-one intermediate. This intermediate can then be converted regioselectively by a second set of reactions to the 3.alpha.-hydroxy,3.beta.-substituted-20-one form, which can be further modified at the 20-keto position.Through this method, each ketone group is independently treated. By modifying the ketones one at a time, one can obtain the desired stereo-specificity at each site.