A formal synthesis of the perhydrogephyrotoxin

A short but uneventful formal synthesis of perhydrogephyrotoxin 3 from readily available tricyclo[5.2.1.0(2,6)]decane derivative 8 via the intermediacy of the cis-hydroindanone 13 is reported. This work constitutes further demonstration of the carbocycle-heterocycle equivalency theme in the synthesis of alkaloids.

A denotational semantics for the generalized ER model and a simple ER algebra

The recent spurt of research activities in Entity-Relationship Approach to databases calls for a close scrutiny of the semantics of the underlying Entity-Relationship models, data manipulation languages, data definition languages, etc. For reasons well known, it is very desirable and sometimes imperative to give formal description of the semantics. In this paper, we consider a specific ER model, the generalized Entity-Relationship model (without attributes on relationships) and give denotational semantics for the model as well as a simple ER algebra based on the model. Our formalism is based on the Vienna Development Method—the meta language (VDM). We also discuss the salient features of the given semantics in detail and suggest directions for further work.

Enantiodivergent Formal Total Synthesis of Aspercyclide C from L-(+)-Tartaric Acid

The enantiodivergent formal syntheses of both enantiomers of aspercyclide C is accomplished. Starting from L-(+)-tartaric acid, the key protected allylic alcohol, (3R,4R)-4-(methoxy-methoxy) non-1-en-3-ol is prepared, and is then elaborated into both enantiomers of 3-(4-methoxybenzyl)oxy]non-1-en-4-ol via Mitsunobu inversion. Esterification with a known biaryl acid, followed by ring-closing metathesis and deprotection completes the syntheses.

Uniform chemical terminology for indian languages

A comparison is made between German and Russian terminological derivations in chemistry and the methods used by Germans and Russians to solve problems related to the fornlrrtion of scientific words. A study of this comparison, it is believed, can help us in the development of scientific words in Indian languages.

A Vicarious One-Pot Transformation of a Fluorocyclitol to a Polycyclitol: Observation of a Formal 4-Fold Axial-Equatorial Epimerization on a Conformationally Locked Scaffold

A conformationally locked fluoropentol undergoes an interesting transformation to (trans,anti,trans,anti,trans)-perhydro-2,3,4a,6,7,8a-naphthalenehexol essentially under conditions of base-induced transesterification. The proposed rationale for the observed metamorphosis involves a nucleophilic displacement of fluoride, and subsequent stereo- and regioselective anti-Furst-Plattner-type ring-opening of the epoxide thus formed.

Formal total synthesis of (+)-didemniserinolipid B

The formal total synthesis of (+)-didemniserinolipid B, a marine tunicate possessing a 6,8-dioxabicyclo3.2.1]octane framework, was accomplished starting from L-(+)-tartaric acid. The key transformations in the synthesis include the elaboration of a gamma-hydroxy-amide readily obtained by desymmetrization of tartaric acid bis-amide via the controlled addition of a Grignard reagent followed by stereoselective reduction of the resulting ketone. (C) 2010 Elsevier Ltd. All rights reserved.

A simple strategy for spirocyclopentannullation of cyclic ketones. Formal total synthesis of (+/-)-acorone

A general and simple methodology for spirocyclopentannulation of cyclic ketones (or 4,4-disubstituted cyclopentenones from acyclic ketones) and its application in the synthesis of the spirodienone 7 via a prochiral precursor constituting a formal total synthesis of (+/-)-acorone (6), are described.

ChemInform Abstract: Enantioselective Formal Total Synthesis of (-)-Homogynolide-A

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Synthesis Based on Cyclohexadienes. 5. A New Approach to the Synthesis of a-Ring Aromatic Steroids - a Formal Total Synthesis of (+/-)-Estrone

A new strategy for the construction of A-ring aromatic steroids which resulted in the formal total synthesis of estrone is described. Thus reaction of the adduct (9), obtained from 1-methoxy-4-methylcyclohexa-1,4-diene and acrolein, with 3-(m-methoxyphenyl)propylmagnesium bromide followed by oxidation afforded the bicyclo[2.2.2]octene derivative (14). Acid-catalysed rearrangement of (14) followed by an intramolecular Michael addition resulted in the cis tetraenone (18) which was dehydrogenated with palladium chloride to the pentaenone (22). Li/NH3 reduction of (22) gave 3-methoxy-D-homoestra-1,3,5(10)-trien-16-one (31) which has been converted into the methyl ether (37) of marrianolic acid, and its methyl ester (38).

A formal total synthesis of (+/-)-enterolactone

A radical cyclization based methodology has been applied for the formal total synthesis of (+/-)-enterolactone (1), the first lignan isolated from human source. Bromoacetalization reaction of the cinnamyl alcohols 7 and 13 using ethyl vinyl ether and NBS, generated the bromoacetals 8 and 15. The 5-exo-trig radical cyclization reaction of the bromoacetals 8 and 15 with in situ generated catalytic tri-a-butyltin hydride and AIBN furnished a 3 : 2 diastereomeric mixture of the cyclic acetals 9 and 16. Sonochemically accelerated Jones oxidation of the cyclic acetals 9 and 16 yielded the gamma-butyrolactones 10 and 12 completing the formal total synthesis of (+/-)-enterolactone. Alternatively radical cyclization of the bromoacetate 17 furnished a 1 : 2 mixture of the lactone 10 and the reduced product 18.

Synthesis based on cyclohexadienes .22. Formal syntheses of patchouli alcohol and norpatchoulenol

The preparation of 6-endo-formyl-1,3,3-trimethylbicyclo[2.2.2]octan-2-one 7 and 6-endo-acetyl-1,3,3-trimethylbicyclo[2.2.2]octan-2-one 8, the two key intermediates for the synthesis of patchouli alcohol 1 and norpatchoulenol 2, is reported by a simple and short method from 2-methylbenzoic acid.

A short, formal synthesis of (+/-)-2-pupukeanone

A short approach to (+/-)-2-pupukeanone, starting from 2,6-dimethylcyclohexenone employing a combination of Michael-Michael reaction and an intramolecular rhodium carbenoid C-H insertion as key reactions, is described.