Apical amide

The metalation of trialkylsilylphosphane and -arsane with the alkaline earth metal bis[bis(trimethylsilyl)amides] of calcium, strontium, and barium yields the mixed phosphanides and phosphanediides as well as arsanides and arsanediides depending on the stoichiometry and the demand of the trialkylsily] substituents according to Scheme 3.6-11. The main feature is the M2E3 bipyramid with the metal atoms in apical positions. These cages are often interconnected via common faces (61, 63, 64, 65, 67, and 69). A substitution of the phosphanide substituents by other Lewis bases such as THF or benzonitrile is not possible for these compounds and, consequently, homoleptic phosphanediides and arsanediides with inner M4E4 heterocubane moieties are so far unknown for M = Ca, Sr, and Ba. In all these cases a further metalation to obtain homoleptic phosphanediides failed. 

The molecular structure consists of three discrete AICI4 tetrahedra and a benzene ring bound to the uranium atom. The coordination around the metal center can be viewed roughly as a pentagonal bip o amid with five equatorial chlorines, an apical chlorine and an apical benzene ring. This coordination is only approximate since the uranium atom lies roughly 0.5 A out of the plane of the equatorial chlorines. The mean AI—Cl distance for the chlorines bonded to the uranium is 2.18 A and 2.09 A for the others. The mean U—C distance is 2.91 A. 

In the synthesis of amidine-functionalized cobalt(III) NsSs-sarco-phaginates, malononitrile was used as a bifunctional carbon acid. The interaction of its pendant nitrile with the coordinated amino group of the [Co(ten)]3+ semiclathrochelate led to the formation of an amidine NsSs-cage with an amide apical substituent. 

Myers et al. found that silyl enolates derived from amides undergo a facile non-catalyzed aldol addition to aldehydes at or below ambient temperature [90]. In particular, the use of cyclic silyl enolate 27, derived from (S)-prolinol propionamide, realizes high levels of diastereoface-selection and simple diastereoselection (anti selectivity) (Scheme 10.27). It has been proposed that this non-catalyzed highly stereoselective reaction proceeds via attack of an aldehyde on 27 to produce a trigonal bipyramidal intermediate 29 in which the aldehyde is apically bound 29 then turns to another isomer 30 by pseudorotation and 30 is then converted into 28 through a six-membered boat-like transition state (rate-determining step). 

Nonsurgical treatments for Graves disease include administration of thion-amide antithyroid drugs, which include propylthiouracil (PTU) and methi-mazole, and/or treatment with radioactive iodine. The thionamides act by inhibiting the enzyme thyroid peroxidase, an enzyme on the apical membrane of the thyroid foUicnlar cell that faces the lumen. This enzyme catalyzes... 

The oxazoline-substituted bismuthine imide has a distorted trigonal bipyr-amidal structure, bearing three ipso carbon atoms at equatorial sites and two nitrogen atoms at apical sites with a Bi-N(imide) bond length of 2.13( 1) A and... 

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