Salt parser exception

error

root@mgmt:/srv/salt# salt "www1.int*" state.highstate 
www1.example.com:
    Data failed to compile:
----------
    Rendering SLS nginx.sites failed, render error: while scanning a double-quoted scalar
  in "<unicode string>", line 140, column 260:
     ... ation_proxy': '{\'/api\': "{\'backend\': \'http://app1.exa ... 
                                         ^
found unknown escape character "'"
  in "<unicode string>", line 140, column 263:
     ... on_proxy': '{\'/api\': "{\'backend\': \'http://app1.examp ... 
                                         ^
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/salt/state.py", line 1944, in render_state
    rendered_sls=mods
  File "/usr/lib/python2.7/dist-packages/salt/template.py", line 69, in compile_template
    ret = render(input_data, env, sls, **render_kwargs)
  File "/usr/lib/python2.7/dist-packages/salt/renderers/yaml.py", line 34, in render
    data = load(yaml_data, Loader=get_yaml_loader(argline))
  File "/usr/lib/python2.7/dist-packages/yaml/__init__.py", line 71, in load
    return loader.get_single_data()
  File "/usr/lib/python2.7/dist-packages/yaml/constructor.py", line 37, in get_single_data
    node = self.get_single_node()
  File "/usr/lib/python2.7/dist-packages/yaml/composer.py", line 36, in get_single_node
    document = self.compose_document()
  File "/usr/lib/python2.7/dist-packages/yaml/composer.py", line 55, in compose_document
    node = self.compose_node(None, None)
  File "/usr/lib/python2.7/dist-packages/yaml/composer.py", line 84, in compose_node
    node = self.compose_mapping_node(anchor)
  File "/usr/lib/python2.7/dist-packages/yaml/composer.py", line 133, in compose_mapping_node
    item_value = self.compose_node(node, item_key)
  File "/usr/lib/python2.7/dist-packages/yaml/composer.py", line 84, in compose_node
    node = self.compose_mapping_node(anchor)
  File "/usr/lib/python2.7/dist-packages/yaml/composer.py", line 133, in compose_mapping_node
    item_value = self.compose_node(node, item_key)
  File "/usr/lib/python2.7/dist-packages/yaml/composer.py", line 82, in compose_node
    node = self.compose_sequence_node(anchor)
  File "/usr/lib/python2.7/dist-packages/yaml/composer.py", line 111, in compose_sequence_node
    node.value.append(self.compose_node(node, index))
  File "/usr/lib/python2.7/dist-packages/yaml/composer.py", line 84, in compose_node
    node = self.compose_mapping_node(anchor)
  File "/usr/lib/python2.7/dist-packages/yaml/composer.py", line 133, in compose_mapping_node
    item_value = self.compose_node(node, item_key)
  File "/usr/lib/python2.7/dist-packages/yaml/composer.py", line 64, in compose_node
    if self.check_event(AliasEvent):
  File "/usr/lib/python2.7/dist-packages/yaml/parser.py", line 98, in check_event
    self.current_event = self.state()
  File "/usr/lib/python2.7/dist-packages/yaml/parser.py", line 449, in parse_block_mapping_value
    if not self.check_token(KeyToken, ValueToken, BlockEndToken):
  File "/usr/lib/python2.7/dist-packages/yaml/scanner.py", line 116, in check_token
    self.fetch_more_tokens()
  File "/usr/lib/python2.7/dist-packages/yaml/scanner.py", line 248, in fetch_more_tokens
    return self.fetch_double()
  File "/usr/lib/python2.7/dist-packages/yaml/scanner.py", line 656, in fetch_double
    self.fetch_flow_scalar(style='"')
  File "/usr/lib/python2.7/dist-packages/yaml/scanner.py", line 667, in fetch_flow_scalar
    self.tokens.append(self.scan_flow_scalar(style))
  File "/usr/lib/python2.7/dist-packages/yaml/scanner.py", line 1156, in scan_flow_scalar
    chunks.extend(self.scan_flow_scalar_non_spaces(double, start_mark))
  File "/usr/lib/python2.7/dist-packages/yaml/scanner.py", line 1230, in scan_flow_scalar_non_spaces
    "found unknown escape character %r" % ch.encode('utf-8'), self.get_mark())
ScannerError: while scanning a double-quoted scalar
  in "<unicode string>", line 140, column 260:
     ... ation_proxy': '{\'/api\': "{\'backend\': \'http://app1.exa ... 
                                         ^
found unknown escape character "'"
  in "<unicode string>", line 140, column 263:
     ... on_proxy': '{\'/api\': "{\'backend\': \'http://app1.exampl ... 
                                         ^

pillar.yaml

nginx_sites:
  - fqdn: example.com
    root: /var/www/example.com
    default: False
    production: False
    aliases:
      - www.example.com
    location_proxy:
      /api:
        backend: http://app1.example.com:7000