Abstract: A vacuum switching valve and a suction system having the same. The vacuum switching valve comprises: a valve body, comprising a first end and a second end, the second end being provided with an air inlet, an air outlet and a through hole; a valve element movably arranged in the valve body; a cylinder, the cylinder being connected to the first end and the valve element, the cylinder drives the valve element to move in the valve body, to close or open the air inlet; a stopper passing through the through hole, the stopper comprising a third end and a fourth end, the third end being connected to the valve element, the fourth end being located on the side of the through hole away from the valve element.

Abstract: The invention relates to a process for preparing a compound of the formula ##STR1## comprising reacting a bromo-substituted pyridine with an amine of the formula NHR.sup.5 R.sup.6, reacting the resulting amide with an iodo-halomethyl-substituted compound and cyclizing the resultant product, wherein R, R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are as defined in the specification; also claimed are a compound of the formula ##STR2## and a process for preparing it from the corresponding halo-substituted benzoic acid.

Abstract: The invention relates to a process for producing a compound of the formula ##STR1## wherein R.sub.1, R.sub.2 and R.sub.

Abstract: The invention relates to a process for preparing a compound of the formula ##STR1## comprising: (a) reacting 2,5-dibromo-3-methylpyridine with an amine of the formula NHR.sup.5 R.sup.6 to obtain an amide;(b) reacting the amide with a compound of formula 3 ##STR2## in the presence of a strong base to obtain a compound of formula 4 ##STR3## (c) converting a compound of formula 4 to the corresponding cyano compound or aldehyde;(d) reacting the cyano compound or aldehyde with a piperidine derivative to obtain an aldehyde or alcohol of formula 7a or 7b, respectively: ##STR4## (e) cyclizing a compound of formula 7a or 7b; wherein R.sup.1 -R.sup.7 are as defined in the specification.

Abstract: The invention relates to a process for producing the compound of the formula ##STR1## which comprises reacting lactone of formula II ##STR2## with an imine of formula III': ##STR3## and converting the resulting chiral diol of formula VI: ##STR4## through several steps to obtain a compound of formula I'.

Abstract: A process for producing a compound of the formula ##STR1## comprises the following sequence of steps: ##STR2## wherein the various radicals are as defined in the specification.

Abstract: Disclosed are a process and intermediates of the formulae ##STR1## wherein R is --CH.sub.2 OH or --OH and R.sup.3 is H or C.sub.1 -C.sub.6 alkyl; useful for preparing benzazepines of the formula ##STR2## having activity as selective D1 antangonists.

Abstract: A process for preparing a compound of formula (IV): ##STR1## comprising a) contacting an oxazoline compound of formula (I): ##STR2## wherein Z is as defined hereinbefore, with a reagent capable of causing an equilibrium between oxazoline compound (I) and an oxazoline compound of formula (II) described herein, and the reagent drives the equilibrium toward oxazoline compound (II) by preferential precipitation of oxazoline compound (II);b) contacting compound (II) with a fluorinating agent to give a fluorinated oxazoline compound of formula (III) described herein; andc) hydrolyzing the compound of formula (III) to formula (IV). In an alternative embodiment, the process is directed toward a process for preparing oxazoline (II) in a single step.

Abstract: The present invention comprises a process for the asymmetric synthesis of florfenicol, thiamphenicol or chloramphenicol, from a derivative of trans-cinnamic acid, comprising the steps:(a) converting the acid to an acid chloride using a chlorinating agent, and reducing the acid chloride to a trans allylic alcohol with a reducing agent;(b) asymmetrically epoxidizing the allylic alcohol of step (a), by reacting with t-butylhydroperoxide in the presence of a chiral epoxidation catalyst prepared from titanium (IV) isopropoxide and L-diisopropyltartaric acid, to form a chiral epoxide;(c) regioselectively opening the epoxide of step (b) by sequentially treating with sodium hydride, zinc chloride and dichloroacetonitrile to form an oxazoline;(d) stereoselective inversion/isomerization of the oxazoline of step (c) by sequentially treating with: (i) a lower alkylsulfonyl chloride and a tertiary amine base; (ii) sulfuric acid and water; (iii) an alkali metal hydroxide; to form an oxazoline;(e) optionally treating the ox