The related marine natural products halichlorine, pinnaic acid, and tauropinnaic acid have been synthesized. The described route provided access to all three compounds from a common, late-stage intermediate. The synthesis began with 1-pyrrolidino-1-cyclopentene from which an intermediate possessing the three contiguous stereocenters of the natural products was synthesized in just four steps. Ol...

Human mitochondria harbor a single type I chaperonin system that is generally thought to function via a unique single-ring intermediate. To date, no crystal structure has been published for any mammalian type I chaperonin complex. In this study, we describe the crystal structure of a football-shaped, double-ring human mitochondrial chaperonin complex at 3.15 Å, which is a novel intermediate, li...

The ‘RING-between-RING’-type E3 ubiquitin ligase HOIP acts via a novel RING/HECT-hybrid ubiquitin transfer mechanism and catalyses the formation of linear ubiquitin chains by non-covalently binding the acceptor ubiquitin. But in the absence of a binding partner, HOIP is autoinhibited. This explains why assembly of either HOIP/ HOIL-1L or HOIP/SHARPIN is required to catalyse linear chain formati...

we introduce center-like subsets z*(r,f), z**(r,f) and z1(r,f), where r is a ring and f is a map from r to r. for f a derivation or a non-identity epimorphism and r a suitably-chosen prime or semiprime ring, we prove that these sets coincide with the center of r.

for an arbitrary ring $r$, the zero-divisor graph of $r$, denoted by $gamma (r)$, is an undirected simple graph that its vertices are all nonzero zero-divisors of $r$ in which any two vertices $x$ and $y$ are adjacent if and only if either $xy=0$ or $yx=0$. it is well-known that for any commutative ring $r$, $gamma (r) cong gamma (t(r))$ where $t(r)$ is the (total) quotient ring of $r$. in this...

let r be a prime ring with extended centroid c, h a generalized derivation of r and n ⩾ 1 a xed integer. in this paper we study the situations: (1) if (h(xy))n = (h(x))n(h(y))n for all x; y 2 r; (2) obtain some related result in case r is a noncommutative banach algebra and h is continuous or spectrally bounded.

a ring $r$ is a strongly clean ring if every element in $r$ is the sum of an idempotent and a unit that commutate. we construct some classes of strongly clean rings which have stable range one. it is shown that such cleanness of $2 imes 2$ matrices over commutative local rings is completely determined in terms of solvability of quadratic equations.

Divergent total syntheses of (-)-kopsifoline D and (-)-deoxoapodine are detailed from a common pentacyclic intermediate 15, enlisting the late-stage formation of two different key strategic bonds (C21-C3 and C21-O-C6) unique to their hexacyclic ring systems that are complementary to its prior use in the total syntheses of kopsinine (C21-C2 bond formation) and (+)-fendleridine (C21-O-C19 bond fo...

in this paper we define a new type of rings ”almost powerhermitian rings” (a generalization of almost hermitian rings) and establish several sufficient conditions over a ring r such that, every regular matrix admits a diagonal power-reduction.