# US 5,705,657 A · Isocyanate process for the preparation of 1,3A,8-trimethyl-1,2,3,3A, 8, 8A-hexahydro-pyrrole ›2,3-B! indol-5 (3AS, 8AR) -hepthylcarbamate

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- Number: US 5,705,657 A
- Document ID: US5705657A
- Status: Granted
- Kind: A
- Application number: 08/416,572
- Filed: 1995-04-04
- Granted: 1998-01-06
- Earliest claimed: 1991-02-14
- Assignees: Labochim Laboratorio Chimico Internazionale S.p.A.
- Inventors: Stefano Maiorana; Anna Bonura; Giorgio Chiodini
- Web page: https://patentgrep.com/patent/US5705657A

## CPC

- C07D 487/04: Ortho-condensed systems
- C07D: HETEROCYCLIC COMPOUNDS (macromolecular compounds C08)

## Abstract

A process for the preparation of 1,3a,8-trimethyl-1,2,3,3a,8,8a-hexahydro-pyrrole›2,3-b!indol-5(3aS,8aR)-he ptylcarbamate, of formula (I) ##STR1## by reacting eseroline with heptylisocyanate in the presence of a metal cyanate and of a quaternary ammonium salt, in polar aprotic solvents.

## Claims

### Claim 1

A process for the preparation of 1,3a,8-trimethyl-1,2,3,3a,8,8a-hexahydro-pyrrole›2,3-b!indol-5(3aS,8aR)-he ptylcarbamate of formula (I): ##STR5## characterized in that eseroline (II) is reacted with heptylisocyanate in the presence of a) catalytic amounts of either a quaternary phosphonium salt R.sup.1 R.sup.2 R.sup.3 R.sup.4 P.sup.+ X.sup.- quaternary ammonium salt R.sup.1 R.sup.2 R.sup.3 R.sup.4 N.sup.+ X.sup.-, wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 can be the same or different and are C.sub.1 -C.sub.12 alkyl or aralkyl and X is an anion, and b) catalytic amounts of a metal cyanate (MeOCN), wherein Me is an alkali metal or the equivalent of an alkaline-earth metal, in a polar aprotic solvent, according to the following scheme: ##STR6##

### Claim 2 (depends on 1)

A process according to claim 1, characterized in that the molar ratio of eseroline to heptylisocyanate is between 1:1 and 1:5.

### Claim 3 (depends on 1)

A process according to claim 1, characterized in that the molar ratio of eseroline to metal cyanate is between 1:0.5 and 1:0.01.

### Claim 4 (depends on 1)

A process according to claim 1, characterized in that the molar ratio of eseroline to quarternary ammonium or phosphonium salt is between 1:0.6 and 1:0.05.

### Claim 5 (depends on 1)

A process according to claim 1, characterized in that acetonitrile is used as the solvent.

### Claim 6 (depends on 1)

A process according to claim 1, characterized in that the reaction is carried out at temperatures comprised between 0.degree. C. and 40.degree. C.

### Claim 7 (depends on 1)

A process according to claim 1, characterized in that eseroline is reacted with heptylisocyanate which is prepared in situ starting from a 1-haloheptane and a metal cyanate in the presence of a quaternary ammonium salt, in the polar aprotic solvent.

### Claim 8 (depends on 1)

A process according to claim 1, wherein Me is potassium; C.sub.1 -C.sub.12 alkyl is ethyl or n-butyl; X is chlorine or bromine.

### Claim 9 (depends on 7)

A process according to claim 7, wherein the 1-haloheptane is 1-bromoheptane and the metal cyanate is potassium cyanate.

### Claim 10 (depends on 7)

A process according to claim 7, wherein the polar aprotic solvent is acetonitrile.

### Claim 11 (depends on 4)

A process according to claim 4, characterized in that the molar ratio of eseroline to quarternary ammonium or phosphonium salt has a value between 1:0.5 and 1:0.2.

### Claim 12 (depends on 2)

A process according to claim 2, characterized in that the molar ratio of eseroline to heptylisocyanate has a value between 1:1 and 1:1.2.

### Claim 13 (depends on 3)

A process according to claim 3, characterized in that the molar ratio of eseroline to metal cyanate has a value between 1:0.4 and 1:0.1.