C-H Functionalization of Amino Alcohols by Osmium Tetroxide/NMO or TPAP/NMO: Protecting Group-Free Synthesis of Indolizidines (-)-223AB and 3-epi -(-)-223AB

2019 ◽  
Vol 2020 (1) ◽  
pp. 103-107 ◽  
Author(s):  
Wei-Lun Chen ◽  
Lee-Ya Wang ◽  
Yu-Jang Li
Keyword(s):  
Osmium Tetroxide ◽  
Amino Alcohols ◽  
Protecting Group

Protecting-group-free synthesis of hydroxyesters from amino alcohols

2020 ◽  
Vol 56 (74) ◽  
pp. 10938-10941
Author(s):  
Guillaume Reynard ◽  
Eve-Marline Joseph-Valcin ◽  
Hélène Lebel
Keyword(s):  
Carboxylic Acids ◽  
Continuous Flow ◽  
Amino Alcohols ◽  
Batch Processes ◽  
Protecting Group

The synthesis of hydroxyesters from carboxylic acids and unprotected amino alcohols in both continuous flow and batch processes is reported.

scholarly journals Cyclic Sulfamidite as Simultaneous Protecting Group for Amino Alcohols: Development of a Mild Deprotection Protocol Using Thiophenol

2020 ◽  
Vol 68 (10) ◽  
pp. 996-1000
Author(s):  
Juri Sakata ◽  
Kazunari Akita ◽  
Manabu Sato ◽  
Masashi Shimomura ◽  
Hidetoshi Tokuyama
Keyword(s):  
Amino Alcohols ◽  
Protecting Group

Cellular Contacts Within the Interhemal Membrane of the Rat Placenta at Term

1974 ◽  
Vol 32 ◽  
pp. 146-147
Author(s):  
William P. Jollie
Keyword(s):  
Osmium Tetroxide ◽  
Uranyl Acetate ◽  
Capillary Endothelium ◽  
En Bloc ◽  
Aldehyde Fixation ◽  
Chorioallantoic Placenta

By routine EM preparative techniques, the tissues which, collectively, separate maternal and fetal bloods in the fully formed chorioallantoic placenta of the rat have been shown to consist of three chorionic layers, or trophoblast, and a layer of allantoic capillary endothelium [Fig. 1]. Relationships between these layers are best demonstrated by special techniques, viz., cacodylate-buffered aldehyde fixation, collidine-buffered osmium tetroxide postfixation, and en bloc staining with uranyl acetate. By using this method on placentas at term, the cells of the outermost chorionic layer (Trophoblast 1) appear to be attached to each other by means of maculae adherentes which sometimes occur in clusters [Fig. 2].

The Ultrastructure of Myocardial Cells in Normal and Cardiac Lethal Mutant Mexican Axolotls, (Ambystoma Mexicanum)

1970 ◽  
Vol 28 ◽  
pp. 62-63
Author(s):  
Larry F. Lemanski ◽  
Eldridge M. Bertke ◽  
J. T. Justus
Keyword(s):  
Fine Structure ◽  
Heart Development ◽  
Osmium Tetroxide ◽  
Picric Acid ◽  
Ambystoma Mexicanum ◽  
Recessive Mutation ◽  
Acid Mixture ◽  
Myocardial Cells ◽  
Lethal Mutant ◽  
Mexican Axolotl

A recessive mutation has been recently described in the Mexican Axolotl, Ambystoma mexicanum; in which the heart forms structurally, but does not contract (Humphrey, 1968. Anat. Rec. 160:475). In this study, the fine structure of myocardial cells from normal (+/+; +/c) and cardiac lethal mutant (c/c) embryos at Harrison's stage 40 was compared. The hearts were fixed in a 0.1 M phosphate buffered formaldehyde-glutaraldehyde-picric acid-styphnic acid mixture and were post fixed in 0.1 M s-collidine buffered 1% osmium tetroxide. A detailed study of heart development in normal and mutant embryos from stages 25-46 will be described elsewhere.

Ultrastructural Lesions Produced by Alcohol and Sucrose in the Heart and Liver of C57BL Mice

1970 ◽  
Vol 28 ◽  
pp. 208-209
Author(s):  
K.K. SEKHRI ◽  
C.S. ALEXANDER ◽  
H.T. NAGASAWA
Keyword(s):  
Osmium Tetroxide ◽  
Male Mice ◽  
Alcohol Group ◽  
Group Iii ◽  
Group I ◽  
C57bl Mice ◽  
Group Ii

C57BL male mice (Jackson Lab., Bar Harbor, Maine) weighing about 18 gms were randomly divided into three groups: group I was fed sweetened liquid alcohol diet (modified Schenkl) in which 36% of the calories were derived from alcohol; group II was maintained on a similar diet but alcohol was isocalorically substituted by sucrose; group III was fed regular mouse chow ad lib for five months. Liver and heart tissues were fixed in 2.5% cacodylate buffered glutaraldehyde, post-fixed in 2% osmium tetroxide and embedded in Epon-araldite.

Spontaneous Cataract in Nude Athymic Mice

1977 ◽  
Vol 35 ◽  
pp. 512-513
Author(s):  
Ronald H. Bradley ◽  
R. S. Berk ◽  
L. D. Hazlett
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Nude Mouse ◽  
Cellular Immunity ◽  
Phosphate Buffer ◽  
Osmium Tetroxide ◽  
Athymic Mice ◽  
Transmission Microscopy ◽  
Mouse Lens ◽  
Scanning Electron

The nude mouse is a hairless mutant (homozygous for the mutation nude, nu/nu), which is born lacking a thymus and possesses a severe defect in cellular immunity. Spontaneous unilateral cataractous lesions were noted (during ocular examination using a stereomicroscope at 40X) in 14 of a series of 60 animals (20%). This transmission and scanning microscopic study characterizes the morphology of this cataract and contrasts these data with normal nude mouse lens.All animals were sacrificed by an ether overdose. Eyes were enucleated and immersed in a mixed fixative (1% osmium tetroxide and 6% glutaraldehyde in Sorenson's phosphate buffer pH 7.4 at 0-4°C) for 3 hours, dehydrated in graded ethanols and embedded in Epon-Araldite for transmission microscopy. Specimens for scanning electron microscopy were fixed similarly, dehydrated in graded ethanols, then to graded changes of Freon 113 and ethanol to 100% Freon 113 and critically point dried in a Bomar critical point dryer using Freon 13 as the transition fluid.

Destruction of Actin Filaments by Osmium Tetroxide

1977 ◽  
Vol 35 ◽  
pp. 466-467
Author(s):  
P. Maupin-Szamier ◽  
T. D. Pollard
Keyword(s):  
Actin Filaments ◽  
Time Course ◽  
Osmium Tetroxide ◽  
Rabbit Muscle ◽  
Muscle Actin ◽  
Sodium Phosphate Buffer ◽  
Transmission Electron ◽  
The Difference ◽  
Rates Of Decay ◽  
Short Time

We have studied the destruction of rabbit muscle actin filaments by osmium tetroxide (OSO4) to develop methods which will preserve the structure of actin filaments during preparation for transmission electron microscopy.Negatively stained F-actin, which appears as smooth, gently curved filaments in control samples (Fig. 1a), acquire an angular, distorted profile and break into progressively shorter pieces after exposure to OSO4 (Fig. 1b,c). We followed the time course of the reaction with viscometry since it is a simple, quantitative method to assess filament integrity. The difference in rates of decay in viscosity of polymerized actin solutions after the addition of four concentrations of OSO4 is illustrated in Fig. 2. Viscometry indicated that the rate of actin filament destruction is also dependent upon temperature, buffer type, buffer concentration, and pH, and requires the continued presence of OSO4. The conditions most favorable to filament preservation are fixation in a low concentration of OSO4 for a short time at 0°C in 100mM sodium phosphate buffer, pH 6.0.

The External Shape of Human γ GI Immunoglobulin from Crystal Sections

1971 ◽  
Vol 29 ◽  
pp. 428-429
Author(s):  
L. W. Labaw
Keyword(s):  
Molecular Weight ◽  
Sodium Phosphate ◽  
Osmium Tetroxide ◽  
Unit Cell ◽  
Monoclinic Space Group ◽  
X Ray ◽  
Large Molecular Weight ◽  
Cell Dimensions ◽  
Unit Cell Dimensions ◽  
Crystallographic Axes

Crystals of a human γGl immunoglobulin have the external morphology of diamond shaped prisms. X-ray studies have shown them to be monoclinic, space group C2, with 2 molecules per unit cell. The unit cell dimensions are a = 194.1, b = 91.7, c = 51.6Å, 8 = 102°. The relatively large molecular weight of 151,000 and these unit cell dimensions made this a promising crystal to study in the EM.Crystals similar to those used in the x-ray studies were fixed at 5°C for three weeks in a solution of mother liquor containing 5 x 10-5M sodium phosphate, pH 7.0, and 0.03% glutaraldehyde. They were postfixed with 1% osmium tetroxide for 15 min. and embedded in Maraglas the usual way. Sections were cut perpendicular to the three crystallographic axes. Such a section cut with its plane perpendicular to the z direction is shown in Fig. 1.This projection of the crystal in the z direction shows periodicities in at least four different directions but these are only seen clearly by sighting obliquely along the micrograph.

Scanning and Transmission Microscopy of Nematocyst Batteries in Epitheliomuscular Cells of Hydra

1971 ◽  
Vol 29 ◽  
pp. 410-411 ◽  
Author(s):  
Jane A. Westfall ◽  
S. Yamataka ◽  
Paul D. Enos
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Osmium Tetroxide ◽  
External Surface ◽  
Three Dimensional ◽  
Surface Structures ◽  
Transmission Microscopy ◽  
Transmission Electron ◽  
Freeze Dried ◽  
Scanning Electron

Scanning electron microscopy (SEM) provides three dimensional details of external surface structures and supplements ultrastructural information provided by transmission electron microscopy (TEM). Animals composed of watery jellylike tissues such as hydras and other coelenterates have not been considered suitable for SEM studies because of the difficulty in preserving such organisms in a normal state. This study demonstrates 1) the successful use of SEM on such tissue, and 2) the unique arrangement of batteries of nematocysts within large epitheliomuscular cells on tentacles of Hydra littoralis.Whole specimens of Hydra were prepared for SEM (Figs. 1 and 2) by the fix, freeze-dry, coat technique of Small and Màrszalek. The specimens were fixed in osmium tetroxide and mercuric chloride, freeze-dried in vacuo on a prechilled 1 Kg brass block, and coated with gold-palladium. Tissues for TEM (Figs. 3 and 4) were fixed in glutaraldehyde followed by osmium tetroxide. Scanning micrographs were taken on a Cambridge Stereoscan Mark II A microscope at 10 KV and transmission micrographs were taken on an RCA EMU 3G microscope (Fig. 3) or on a Hitachi HU 11B microscope (Fig. 4).

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